Publications by Department of Physics of Nanostructures
Departments of ISQI | Publications of ISQI
2023 |
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| 72. | Bivas Rana, YoshiChika Otani Anisotropy of magnetic damping in Ta/CoFeB/MgO heterostructures Scientific Reports, 13 (1), pp. 8532, 2023, ISSN: 2045-2322. @article{rana_anisotropy_2023, title = {Anisotropy of magnetic damping in Ta/CoFeB/MgO heterostructures}, author = {Bivas Rana and YoshiChika Otani}, url = {https://www.nature.com/articles/s41598-023-35739-8}, doi = {10.1038/s41598-023-35739-8}, issn = {2045-2322}, year = {2023}, date = {2023-05-26}, urldate = {2023-05-28}, journal = {Scientific Reports}, volume = {13}, number = {1}, pages = {8532}, abstract = {Magnetic damping controls the performance and operational speed of many spintronics devices. Being a tensor quantity, the damping in magnetic thin films often shows anisotropic behavior with the magnetization orientation. Here, we have studied the anisotropy of damping in Ta/CoFeB/MgO heterostructures, deposited on thermally oxidized Si substrates, as a function of the orientation of magnetization. By performing ferromagnetic resonance (FMR) measurements based on spin pumping and inverse spin Hall effect (ISHE), we extract the damping parameter in those films and find that the anisotropy of damping contains four-fold and two-fold anisotropy terms. We infer that four-fold anisotropy originates from two-magnon scattering (TMS). By studying reference Ta/CoFeB/MgO films, deposited on LiNbO3 substrates, we find that the two-fold anisotropy is correlated with in-plane magnetic anisotropy (IMA) of the films, suggesting its origin as the anisotropy in bulk spin–orbit coupling (SOC) of CoFeB film. We conclude that when IMA is very small, it’s correlation with two-fold anisotropy cannot be experimentally identified. However, as IMA increases, it starts to show a correlation with two-fold anisotropy in damping. These results will be beneficial for designing future spintronics devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnetic damping controls the performance and operational speed of many spintronics devices. Being a tensor quantity, the damping in magnetic thin films often shows anisotropic behavior with the magnetization orientation. Here, we have studied the anisotropy of damping in Ta/CoFeB/MgO heterostructures, deposited on thermally oxidized Si substrates, as a function of the orientation of magnetization. By performing ferromagnetic resonance (FMR) measurements based on spin pumping and inverse spin Hall effect (ISHE), we extract the damping parameter in those films and find that the anisotropy of damping contains four-fold and two-fold anisotropy terms. We infer that four-fold anisotropy originates from two-magnon scattering (TMS). By studying reference Ta/CoFeB/MgO films, deposited on LiNbO3 substrates, we find that the two-fold anisotropy is correlated with in-plane magnetic anisotropy (IMA) of the films, suggesting its origin as the anisotropy in bulk spin–orbit coupling (SOC) of CoFeB film. We conclude that when IMA is very small, it’s correlation with two-fold anisotropy cannot be experimentally identified. However, as IMA increases, it starts to show a correlation with two-fold anisotropy in damping. These results will be beneficial for designing future spintronics devices. |
| 71. | Dariia Popadiuk, Elena V. Tartakovskaya, Maciej Krawczyk, Kostyantyn Guslienko Emergent Magnetic Field and Nonzero Gyrovector of the Toroidal Magnetic Hopfion physica status solidi (RRL) – Rapid Research Letters, n/a (n/a), pp. 2300131, 2023. @article{https://doi.org/10.1002/pssr.202300131, title = {Emergent Magnetic Field and Nonzero Gyrovector of the Toroidal Magnetic Hopfion}, author = {Dariia Popadiuk and Elena V. Tartakovskaya and Maciej Krawczyk and Kostyantyn Guslienko}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/pssr.202300131}, doi = {https://doi.org/10.1002/pssr.202300131}, year = {2023}, date = {2023-05-13}, journal = {physica status solidi (RRL) – Rapid Research Letters}, volume = {n/a}, number = {n/a}, pages = {2300131}, abstract = {Magnetic hopfions are localized magnetic solitons with a nonzero 3D topological charge (Hopf index). Herein, an analytical calculation of the magnetic hopfion gyrovector is presented and it is shown that it does not vanish even in an infinite sample. The calculation method is based on the concept of the emergent magnetic field. The particular case of the simplest nontrivial toroidal hopfion with the Hopf index | QH |=1$łeft|right. Q_textĦ łeft|right. = 1$ in the cylindrical magnetic dot is considered and dependencies of the gyrovector components on the dot sizes are calculated. Nonzero hopfion gyrovector is important in any description of the hopfion dynamics within the collective coordinate Thiele's approach.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnetic hopfions are localized magnetic solitons with a nonzero 3D topological charge (Hopf index). Herein, an analytical calculation of the magnetic hopfion gyrovector is presented and it is shown that it does not vanish even in an infinite sample. The calculation method is based on the concept of the emergent magnetic field. The particular case of the simplest nontrivial toroidal hopfion with the Hopf index | QH |=1$łeft|right. Q_textĦ łeft|right. = 1$ in the cylindrical magnetic dot is considered and dependencies of the gyrovector components on the dot sizes are calculated. Nonzero hopfion gyrovector is important in any description of the hopfion dynamics within the collective coordinate Thiele's approach. |
| 70. | R Mehta, Mathieu Moalic, Maciej Krawczyk, S Saha Tunability of spin-wave spectra in a 2D triangular shaped magnonic fractals Journal of Physics: Condensed Matter, 35 (32), pp. 324002, 2023. @article{Mehta_2023, title = {Tunability of spin-wave spectra in a 2D triangular shaped magnonic fractals}, author = {R Mehta and Mathieu Moalic and Maciej Krawczyk and S Saha}, url = {https://dx.doi.org/10.1088/1361-648X/acd15f}, doi = {10.1088/1361-648X/acd15f}, year = {2023}, date = {2023-05-12}, journal = {Journal of Physics: Condensed Matter}, volume = {35}, number = {32}, pages = {324002}, publisher = {IOP Publishing}, abstract = {Reprogramming the structure of the magnonic bands during their operation is important for controlling spin waves in magnonic devices. Here, we report the tunability of the spin-wave spectra for a triangular shaped deterministic magnonic fractal, which is known as Sierpinski triangle by solving the Landau–Lifshitz–Gilbert equation using a micromagnetic simulations. The spin-wave dynamics change significantly with the variation of iteration number. A wide frequency gap is observed for a structure with an iteration number exceeding some value and a plenty of mini-frequency bandgaps at structures with high iteration number. The frequency gap could be controlled by varying the strength of the magnetic field. A sixfold symmetry in the frequency gap is observed with the variation of the azimuthal angle of the external magnetic field. The spatial distributions of the spin-wave modes allow to identify the bands surrounding the gap. The observations are important for the application of magnetic fractals as a reconfigurable aperiodic magnonic crystals.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Reprogramming the structure of the magnonic bands during their operation is important for controlling spin waves in magnonic devices. Here, we report the tunability of the spin-wave spectra for a triangular shaped deterministic magnonic fractal, which is known as Sierpinski triangle by solving the Landau–Lifshitz–Gilbert equation using a micromagnetic simulations. The spin-wave dynamics change significantly with the variation of iteration number. A wide frequency gap is observed for a structure with an iteration number exceeding some value and a plenty of mini-frequency bandgaps at structures with high iteration number. The frequency gap could be controlled by varying the strength of the magnetic field. A sixfold symmetry in the frequency gap is observed with the variation of the azimuthal angle of the external magnetic field. The spatial distributions of the spin-wave modes allow to identify the bands surrounding the gap. The observations are important for the application of magnetic fractals as a reconfigurable aperiodic magnonic crystals. |
| 69. | J M Flores-Camacho, Bivas Rana, R E Balderas-Navarro, A Lastras-Martínez, Yoshichika Otani, Jorge Puebla Mid-infrared optical properties of non-magnetic-metal/CoFeB/MgO heterostructures Journal of Physics D: Applied Physics, 56 (31), pp. 315301, 2023. @article{Flores-Camacho_2023, title = {Mid-infrared optical properties of non-magnetic-metal/CoFeB/MgO heterostructures}, author = {J M Flores-Camacho and Bivas Rana and R E Balderas-Navarro and A Lastras-Martínez and Yoshichika Otani and Jorge Puebla}, url = {https://dx.doi.org/10.1088/1361-6463/acd00f}, doi = {10.1088/1361-6463/acd00f}, year = {2023}, date = {2023-05-09}, journal = {Journal of Physics D: Applied Physics}, volume = {56}, number = {31}, pages = {315301}, publisher = {IOP Publishing}, abstract = {We report on the optical characterization of non-magnetic metal (NM)/ferromagnetic (Co20Fe60B20)/MgO heterostructures and interfaces by using mid infrared (MIR) spectroscopic ellipsometry at room temperature. We extracted for the MIR range the dielectric function (DF) of Co20Fe60B20, that is lacking in literature, from a multisample analysis. From the optical modeling of the heterostructures we detected and determined the dielectric tensor properties of a two-dimensional electron gas (2DEG) forming at the NM and the CoFeB interface. These properties comprise independent Drude parameters for the in-plane and out-of plane tensor components, with the latter having an epsilon-near-zero frequency within our working spectral range. A feature assigned to spin–orbit coupling (SOC) is identified. Furthermore, it is found that both, the interfacial properties, 2DEG Drude parameters and SOC strength, and the apparent DF of the MgO layer depend on the type of the underlying NM, namely, Pt, W, or Cu. The results reported here should be useful in tailoring novel phenomena in such types of heterostructures by assessing their optical response noninvasively, complementing existing characterization tools such as angle-resolved photoemission spectroscopy, and those related to electron/spin transport.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report on the optical characterization of non-magnetic metal (NM)/ferromagnetic (Co20Fe60B20)/MgO heterostructures and interfaces by using mid infrared (MIR) spectroscopic ellipsometry at room temperature. We extracted for the MIR range the dielectric function (DF) of Co20Fe60B20, that is lacking in literature, from a multisample analysis. From the optical modeling of the heterostructures we detected and determined the dielectric tensor properties of a two-dimensional electron gas (2DEG) forming at the NM and the CoFeB interface. These properties comprise independent Drude parameters for the in-plane and out-of plane tensor components, with the latter having an epsilon-near-zero frequency within our working spectral range. A feature assigned to spin–orbit coupling (SOC) is identified. Furthermore, it is found that both, the interfacial properties, 2DEG Drude parameters and SOC strength, and the apparent DF of the MgO layer depend on the type of the underlying NM, namely, Pt, W, or Cu. The results reported here should be useful in tailoring novel phenomena in such types of heterostructures by assessing their optical response noninvasively, complementing existing characterization tools such as angle-resolved photoemission spectroscopy, and those related to electron/spin transport. |
| 68. | Andriy E. Serebryannikov, Diana C Skigin, Hodjat Hajian, Ekmel Ozbay J. Opt. Soc. Am. B, 40 (5), pp. 1340–1349, 2023. @article{Serebryannikov:23, title = {Wide-angle and simultaneously wideband blazing (deflection) enabling multifunctionality in metagratings comprising epsilon-near-zero materials}, author = {Andriy E. Serebryannikov and Diana C Skigin and Hodjat Hajian and Ekmel Ozbay}, url = {https://opg.optica.org/josab/abstract.cfm?URI=josab-40-5-1340}, doi = {10.1364/JOSAB.485457}, year = {2023}, date = {2023-05-01}, journal = {J. Opt. Soc. Am. B}, volume = {40}, number = {5}, pages = {1340--1349}, publisher = {Optica Publishing Group}, abstract = {This paper investigates diffractions by gratings made of a dispersive material in an epsilon-near-zero (ENZ) regime and having one-side corrugations, and those by two-component dielectric-ENZ gratings with the inner corrugations and flat outer interfaces. The goal is to achieve wideband and simultaneously wide-angle textminus1st order blazing (deflection) that may enable wideband spatial filtering and demultiplexing in reflection mode. Several typical scenarios are discussed, which differ in the maximum magnitude of the blazed wave and size of the blazing area observed on the frequency-incidence angle plane, as well as the contribution of the ranges of positive and negative permittivity in the vicinity of zero. The high capability of ENZ and dielectric-ENZ gratings in asymmetric reflection is demonstrated for three different levels of losses for the dispersive material.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper investigates diffractions by gratings made of a dispersive material in an epsilon-near-zero (ENZ) regime and having one-side corrugations, and those by two-component dielectric-ENZ gratings with the inner corrugations and flat outer interfaces. The goal is to achieve wideband and simultaneously wide-angle textminus1st order blazing (deflection) that may enable wideband spatial filtering and demultiplexing in reflection mode. Several typical scenarios are discussed, which differ in the maximum magnitude of the blazed wave and size of the blazing area observed on the frequency-incidence angle plane, as well as the contribution of the ranges of positive and negative permittivity in the vicinity of zero. The high capability of ENZ and dielectric-ENZ gratings in asymmetric reflection is demonstrated for three different levels of losses for the dispersive material. |
| 67. | Arezoo Etesamirad, Yulia Kharlan, Rodolfo Rodriguez, Igor Barsukov, Roman Verba Controlling Selection Rules for Magnon Scattering in Nanomagnets by Spatial Symmetry Breaking Phys. Rev. Appl., 19 , pp. 044087, 2023. @article{PhysRevApplied.19.044087, title = {Controlling Selection Rules for Magnon Scattering in Nanomagnets by Spatial Symmetry Breaking}, author = {Arezoo Etesamirad and Yulia Kharlan and Rodolfo Rodriguez and Igor Barsukov and Roman Verba}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.19.044087}, doi = {10.1103/PhysRevApplied.19.044087}, year = {2023}, date = {2023-04-27}, journal = {Phys. Rev. Appl.}, volume = {19}, pages = {044087}, publisher = {American Physical Society}, abstract = {Nanomagnets are the building blocks of many existing and emergent spintronic technologies. The magnetization dynamics of nanomagnets is often dominated by nonlinear processes, which have been recently shown to have many surprising features and far-reaching implications for applications. Here we develop a theoretical framework uncovering the selection rules for multimagnon processes and discuss their underlying mechanisms. For its technological relevance, we focus on the degenerate three-magnon process in thin elliptical nanodisks to illustrate our findings. We parameterize the selection rules through a set of magnon interaction coefficients which we calculate using micromagnetic simulations. We postulate the selection rules and investigate how they are altered by perturbations that break the symmetry of static magnetization configuration and spatial spin-wave profiles and that can be realized by applying off-symmetry-axis or nonuniform magnetic fields. Our work provides the phenomenological understanding of the mechanics of magnon interaction as well as the formalism for determining the interaction coefficients from simulations and experimental data. Our results serve as a guide to analyze the magnon processes inherently present in spin-torque devices in order to boost their performance or to engineer a specific nonlinear response in a nanomagnet used in a neuromorphic or quantum magnonic application.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nanomagnets are the building blocks of many existing and emergent spintronic technologies. The magnetization dynamics of nanomagnets is often dominated by nonlinear processes, which have been recently shown to have many surprising features and far-reaching implications for applications. Here we develop a theoretical framework uncovering the selection rules for multimagnon processes and discuss their underlying mechanisms. For its technological relevance, we focus on the degenerate three-magnon process in thin elliptical nanodisks to illustrate our findings. We parameterize the selection rules through a set of magnon interaction coefficients which we calculate using micromagnetic simulations. We postulate the selection rules and investigate how they are altered by perturbations that break the symmetry of static magnetization configuration and spatial spin-wave profiles and that can be realized by applying off-symmetry-axis or nonuniform magnetic fields. Our work provides the phenomenological understanding of the mechanics of magnon interaction as well as the formalism for determining the interaction coefficients from simulations and experimental data. Our results serve as a guide to analyze the magnon processes inherently present in spin-torque devices in order to boost their performance or to engineer a specific nonlinear response in a nanomagnet used in a neuromorphic or quantum magnonic application. |
| 66. | Jan Kisielewski, Paweł Gruszecki, Maciej Krawczyk, Vitalii Zablotskii, Andrzej Maziewski Between waves and patterns: Spin wave freezing in films with Dzyaloshinskii-Moriya interaction Phys. Rev. B, 107 , pp. 134416, 2023. @article{PhysRevB.107.134416, title = {Between waves and patterns: Spin wave freezing in films with Dzyaloshinskii-Moriya interaction}, author = {Jan Kisielewski and Paweł Gruszecki and Maciej Krawczyk and Vitalii Zablotskii and Andrzej Maziewski}, url = {https://link.aps.org/doi/10.1103/PhysRevB.107.134416}, doi = {10.1103/PhysRevB.107.134416}, year = {2023}, date = {2023-04-12}, journal = {Phys. Rev. B}, volume = {107}, pages = {134416}, publisher = {American Physical Society}, abstract = {The relationship between waves and static pattern formation is an intriguing effect and remains unexplained in many areas of physics, including magnetism. We study the spin-wave-mediated spin reorientation transition (SRT) in magnetic films with uniaxial magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI). In particular, we show that propagating spin waves can freeze in the SRT, causing periodic magnetic domains to arise, which is reminiscent of the wave amplitude distribution. This process can take place under the influence of a change in the magnetic field, but also of other parameters. Interestingly, at the SRT, DMI nonreciprocity leads to the emergence of flowing magnetization patterns, which suggests a spontaneous breaking of translational symmetry, and the formation of magnonic space-time crystals. The described phenomena are general and should take place in a large family of magnetic materials. Therefore, the results should be of great importance for the further development of spintronics and magnonics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The relationship between waves and static pattern formation is an intriguing effect and remains unexplained in many areas of physics, including magnetism. We study the spin-wave-mediated spin reorientation transition (SRT) in magnetic films with uniaxial magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI). In particular, we show that propagating spin waves can freeze in the SRT, causing periodic magnetic domains to arise, which is reminiscent of the wave amplitude distribution. This process can take place under the influence of a change in the magnetic field, but also of other parameters. Interestingly, at the SRT, DMI nonreciprocity leads to the emergence of flowing magnetization patterns, which suggests a spontaneous breaking of translational symmetry, and the formation of magnonic space-time crystals. The described phenomena are general and should take place in a large family of magnetic materials. Therefore, the results should be of great importance for the further development of spintronics and magnonics. |
| 65. | Angshuman Deka, Bivas Rana, YoshiChika Otani, Yasuhiro Fukuma Journal of Physics: Condensed Matter, 35 (21), pp. 214003, 2023. @article{Deka_2023, title = {Ferromagnetic resonance excited by interfacial microwave electric field: the role of current-induced torques}, author = {Angshuman Deka and Bivas Rana and YoshiChika Otani and Yasuhiro Fukuma}, url = {https://dx.doi.org/10.1088/1361-648X/acc377}, doi = {10.1088/1361-648X/acc377}, year = {2023}, date = {2023-03-24}, journal = {Journal of Physics: Condensed Matter}, volume = {35}, number = {21}, pages = {214003}, publisher = {IOP Publishing}, abstract = {Excitation of magnetization dynamics in magnetic materials, especially in ultrathin ferromagnetic films, is of utmost importance for developing various ultrafast spintronics devices. Recently, the excitation of magnetization dynamics, i.e. ferromagnetic resonance (FMR) via electric field-induced modulation of interfacial magnetic anisotropies, has received particular attention due to several advantages, including lower power consumption. However, several additional torques generated by unavoidable microwave current induced because of the capacitive nature of the junctions may also contribute to the excitation of FMR apart from electric field-induced torques. Here, we study the FMR signals excited by applying microwave signal across the metal-oxide junction in CoFeB/MgO heterostructures with Pt and Ta buffer layers. Analysis of the resonance line shape and angular dependent behavior of resonance amplitude revealed that apart from voltage-controlled in-plane magnetic anisotropy (VC-IMA) torque a significant contribution can also arises from spin-torques and Oersted field torques originating from the flow of microwave current through metal-oxide junction. Surprisingly, the overall contribution from spin-torques and Oersted field torques are comparable to the VC-IMA torque contribution, even for a device with negligible defects. This study will be beneficial for designing future electric field-controlled spintronics devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Excitation of magnetization dynamics in magnetic materials, especially in ultrathin ferromagnetic films, is of utmost importance for developing various ultrafast spintronics devices. Recently, the excitation of magnetization dynamics, i.e. ferromagnetic resonance (FMR) via electric field-induced modulation of interfacial magnetic anisotropies, has received particular attention due to several advantages, including lower power consumption. However, several additional torques generated by unavoidable microwave current induced because of the capacitive nature of the junctions may also contribute to the excitation of FMR apart from electric field-induced torques. Here, we study the FMR signals excited by applying microwave signal across the metal-oxide junction in CoFeB/MgO heterostructures with Pt and Ta buffer layers. Analysis of the resonance line shape and angular dependent behavior of resonance amplitude revealed that apart from voltage-controlled in-plane magnetic anisotropy (VC-IMA) torque a significant contribution can also arises from spin-torques and Oersted field torques originating from the flow of microwave current through metal-oxide junction. Surprisingly, the overall contribution from spin-torques and Oersted field torques are comparable to the VC-IMA torque contribution, even for a device with negligible defects. This study will be beneficial for designing future electric field-controlled spintronics devices. |
| 64. | Oleksandr Pastukh, Malgorzata Kac, Svitlana Pastukh, Dominika Kuźma, Mateusz Zelent, Maciej Krawczyk, Łukasz Laskowski Magnetic Behavior of the Arrays of Iron Cylindrical Nanostructures: Atomistic Spin Model Simulations Crystals, 13 (3), 2023, ISSN: 2073-4352. @article{cryst13030537, title = {Magnetic Behavior of the Arrays of Iron Cylindrical Nanostructures: Atomistic Spin Model Simulations}, author = {Oleksandr Pastukh and Malgorzata Kac and Svitlana Pastukh and Dominika Kuźma and Mateusz Zelent and Maciej Krawczyk and Łukasz Laskowski}, url = {https://www.mdpi.com/2073-4352/13/3/537}, doi = {10.3390/cryst13030537}, issn = {2073-4352}, year = {2023}, date = {2023-03-21}, journal = {Crystals}, volume = {13}, number = {3}, abstract = {Cylindrical ferromagnetic nanowires are of particular interest in nanomaterials science due to various manufacturing methods and a wide range of applications in nanotechnology, with special attention given to those with diameters less than the single domain limit. In the current study, the simulations of magnetic properties of isolated iron nanowires with a diameter of 5 nm and various aspect ratios, as well as two types of arrays of such nanowires (with hexagonal and square arrangement), were performed using atomistic spin model. In the case of a single nanowire, change of coercive field for different applied field directions with aspect ratio was discussed. It was shown that the evolution of the magnetization reversal mechanism from coherent rotation to domain wall propagation appears with increasing length of single nanowire. For the arrays of cylindrical nanostructures, it was revealed that different number of nearest neighbors for each nanostructure in square and hexagonal arrays have an influence on their magnetostatic interactions, which are the most significant for shortest interwire distances. The corresponding spin configurations during the remagnetization process showed the appearance of intermediate magnetization states (when a part of wires is magnetized parallel and part antiparallel to the field direction), connected with Barkhausen effect, which influence the observed hysteresis curves.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cylindrical ferromagnetic nanowires are of particular interest in nanomaterials science due to various manufacturing methods and a wide range of applications in nanotechnology, with special attention given to those with diameters less than the single domain limit. In the current study, the simulations of magnetic properties of isolated iron nanowires with a diameter of 5 nm and various aspect ratios, as well as two types of arrays of such nanowires (with hexagonal and square arrangement), were performed using atomistic spin model. In the case of a single nanowire, change of coercive field for different applied field directions with aspect ratio was discussed. It was shown that the evolution of the magnetization reversal mechanism from coherent rotation to domain wall propagation appears with increasing length of single nanowire. For the arrays of cylindrical nanostructures, it was revealed that different number of nearest neighbors for each nanostructure in square and hexagonal arrays have an influence on their magnetostatic interactions, which are the most significant for shortest interwire distances. The corresponding spin configurations during the remagnetization process showed the appearance of intermediate magnetization states (when a part of wires is magnetized parallel and part antiparallel to the field direction), connected with Barkhausen effect, which influence the observed hysteresis curves. |
| 63. | J Feilhauer, Mateusz Zelent, Zhiwang Zhang, J Christensen, M Mruczkiewicz Unidirectional spin-wave edge modes in magnonic crystal APL Materials, 11 (2), pp. 021104, 2023. @article{doi:10.1063/5.0134099, title = {Unidirectional spin-wave edge modes in magnonic crystal}, author = {J Feilhauer and Mateusz Zelent and Zhiwang Zhang and J Christensen and M Mruczkiewicz}, url = {https://doi.org/10.1063/5.0134099}, doi = {10.1063/5.0134099}, year = {2023}, date = {2023-02-13}, journal = {APL Materials}, volume = {11}, number = {2}, pages = {021104}, abstract = {We present a numerical demonstration of magnonic crystals hosting unidirectional, topologically protected edge states. The magnonic crystal is formed of dipolarly coupled Permalloy triangles. We show that due to the geometry of the block, the size of the structure can be scaled up. In addition, edge states can be found over a wide frequency range. Experimental detection of edge excitations in the considered system can be done with state-of-the-art techniques. Thus, we demonstrate a proof-of-concept magnonic Chern topological insulator nanostructure with simple geometry feasible for experimental realization. Furthermore, by tuning the strength of the perpendicular magnetic field, we induce a topological phase transition, which results in the change of direction of the topological edge state. Then, we demonstrate the magnonic switch based on this effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a numerical demonstration of magnonic crystals hosting unidirectional, topologically protected edge states. The magnonic crystal is formed of dipolarly coupled Permalloy triangles. We show that due to the geometry of the block, the size of the structure can be scaled up. In addition, edge states can be found over a wide frequency range. Experimental detection of edge excitations in the considered system can be done with state-of-the-art techniques. Thus, we demonstrate a proof-of-concept magnonic Chern topological insulator nanostructure with simple geometry feasible for experimental realization. Furthermore, by tuning the strength of the perpendicular magnetic field, we induce a topological phase transition, which results in the change of direction of the topological edge state. Then, we demonstrate the magnonic switch based on this effect. |
| 62. | Liubov Ivzhenko, Aleksey Girich, Artem Hrinchenko, Oleh Yermakov 2022 IEEE 2nd Ukrainian Microwave Week (UkrMW), pp. 214-217, 2023. @inproceedings{10037146, title = {Mechanically Tunable Topological Transition and High-Directional Propagation of Surface Waves at Bilayer Hyperbolic Metasurfaces}, author = {Liubov Ivzhenko and Aleksey Girich and Artem Hrinchenko and Oleh Yermakov}, doi = {10.1109/UkrMW58013.2022.10037146}, year = {2023}, date = {2023-02-13}, booktitle = {2022 IEEE 2nd Ukrainian Microwave Week (UkrMW)}, pages = {214-217}, abstract = {We propose simple and efficient way to control the propagation regime and direction of spoof surface plasmon-polaritons localized at bilayer hyperbolic metasurfaces. We demonstrate the photonic topological transition at the same frequency implemented with a mutual rotation of the metasurface layers. Finally, we show the tunable multidirectional in-plane canalization of surface waves adjusting by the interlayer coupling. These results discover new opportunities for the manipulation over surface waves at metasurfaces.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } We propose simple and efficient way to control the propagation regime and direction of spoof surface plasmon-polaritons localized at bilayer hyperbolic metasurfaces. We demonstrate the photonic topological transition at the same frequency implemented with a mutual rotation of the metasurface layers. Finally, we show the tunable multidirectional in-plane canalization of surface waves adjusting by the interlayer coupling. These results discover new opportunities for the manipulation over surface waves at metasurfaces. |
| 61. | Sergey Polevoy, Ganna Kharchenko, Tetiana Kalmykova, Yevhenii Ostryzhnyi, Liubov Ivzhenko, Oleh Yermakov Polarization-Controlled Excitation of Surface Waves at Self-Complementary Metasurface 2022 IEEE 2nd Ukrainian Microwave Week (UkrMW), pp. 222-225, 2023. @inproceedings{10036966, title = {Polarization-Controlled Excitation of Surface Waves at Self-Complementary Metasurface}, author = {Sergey Polevoy and Ganna Kharchenko and Tetiana Kalmykova and Yevhenii Ostryzhnyi and Liubov Ivzhenko and Oleh Yermakov}, doi = {10.1109/UkrMW58013.2022.10036966}, year = {2023}, date = {2023-02-13}, booktitle = {2022 IEEE 2nd Ukrainian Microwave Week (UkrMW)}, pages = {222-225}, abstract = {In this work, we study the surface electromagnetic waves propagating along the self-complementary metasurface. We propose a way to excite the surface waves of the necessary polarization by using the TE-TM degeneracy property of the self-complementary metasurface. In particular, we demonstrate the excitation of surface waves with linear horizontal, vertical and diagonal as well as circular polarizations. The proposed technique opens new possibilities for the in-plane signal transferring and transformation.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } In this work, we study the surface electromagnetic waves propagating along the self-complementary metasurface. We propose a way to excite the surface waves of the necessary polarization by using the TE-TM degeneracy property of the self-complementary metasurface. In particular, we demonstrate the excitation of surface waves with linear horizontal, vertical and diagonal as well as circular polarizations. The proposed technique opens new possibilities for the in-plane signal transferring and transformation. |
| 60. | Paweł Gruszecki, Jan Kisielewski Scientific Reports, 13 (1), pp. 1218, 2023, ISSN: 2045-2322. @article{gruszecki_influence_2023, title = {Influence of Dzyaloshinskii–Moriya interaction and perpendicular anisotropy on spin waves propagation in stripe domain patterns and spin spirals}, author = {Paweł Gruszecki and Jan Kisielewski}, url = {https://www.nature.com/articles/s41598-023-28271-2}, doi = {10.1038/s41598-023-28271-2}, issn = {2045-2322}, year = {2023}, date = {2023-01-01}, urldate = {2023-01-25}, journal = {Scientific Reports}, volume = {13}, number = {1}, pages = {1218}, abstract = {Texture-based magnonics focuses on the utilization of spin waves in magnetization textures to process information. Using micromagnetic simulations, we study how (1) the dynamic magnetic susceptibility, (2) dispersion relations, and (3) the equilibrium magnetic configurations in periodic magnetization textures in a ultrathin ferromagnetic film in remanence depend on the values of the Dzyaloshinskii–Moriya interaction and the perpendicular magnetocrystalline anisotropy. We observe that for large Dzyaloshinskii–Moriya interaction values, spin spirals with periods of tens of nanometers are the preferred state; for small Dzyaloshinskii–Moriya interaction values and large anisotropies, stripe domain patterns with over a thousand times larger period are preferable. We observe and explain the selectivity of the excitation of resonant modes by a linearly polarized microwave field. We study the propagation of spin waves along and perpendicular to the direction of the periodicity. For propagation along the direction of the periodicity, we observe a bandgap that closes and reopens, which is accompanied by a swap in the order of the bands. For waves propagating in the perpendicular direction, some modes can be used for unidirectional channeling of spin waves. Overall, our findings are promising in sensing and signal processing applications and explain the fundamental properties of periodic magnetization textures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Texture-based magnonics focuses on the utilization of spin waves in magnetization textures to process information. Using micromagnetic simulations, we study how (1) the dynamic magnetic susceptibility, (2) dispersion relations, and (3) the equilibrium magnetic configurations in periodic magnetization textures in a ultrathin ferromagnetic film in remanence depend on the values of the Dzyaloshinskii–Moriya interaction and the perpendicular magnetocrystalline anisotropy. We observe that for large Dzyaloshinskii–Moriya interaction values, spin spirals with periods of tens of nanometers are the preferred state; for small Dzyaloshinskii–Moriya interaction values and large anisotropies, stripe domain patterns with over a thousand times larger period are preferable. We observe and explain the selectivity of the excitation of resonant modes by a linearly polarized microwave field. We study the propagation of spin waves along and perpendicular to the direction of the periodicity. For propagation along the direction of the periodicity, we observe a bandgap that closes and reopens, which is accompanied by a swap in the order of the bands. For waves propagating in the perpendicular direction, some modes can be used for unidirectional channeling of spin waves. Overall, our findings are promising in sensing and signal processing applications and explain the fundamental properties of periodic magnetization textures. |
| 59. | Shashank Shekhar, Sławomir Mielcarek, Y Otani, Bivas Rana, Aleksandra Trzaskowska Influence of CoFeB layer thickness on elastic parameters in CoFeB/MgO heterostructures Scientific Reports, 13 (1), pp. 10668, 2023, ISSN: 2045-2322. @article{shekhar_influence_2023, title = {Influence of CoFeB layer thickness on elastic parameters in CoFeB/MgO heterostructures}, author = {Shashank Shekhar and Sławomir Mielcarek and Y Otani and Bivas Rana and Aleksandra Trzaskowska}, url = {https://www.nature.com/articles/s41598-023-37808-4}, doi = {10.1038/s41598-023-37808-4}, issn = {2045-2322}, year = {2023}, date = {2023-01-01}, urldate = {2023-07-04}, journal = {Scientific Reports}, volume = {13}, number = {1}, pages = {10668}, abstract = {The surface acoustic waves, i.e., surface phonons may have huge potential for future spintronic devices, if coupled to other waves (e.g., spin waves) or quasiparticles. In order to understand the coupling of acoustic phonons with the spin degree of freedom, especially in magnetic thin film-based heterostructures, one needs to investigate the properties of phonons in those heterostructures. This also allows us to determine the elastic properties of individual magnetic layers and the effective elastic parameters of the whole stacks. Here, we study frequency versus wavevector dispersion of thermally excited SAWs in CoFeB/MgO heterostructures with varying CoFeB thickness by employing Brillouin light spectroscopy. The experimental results are corroborated by finite element method-based simulations. From the best agreement of simulation results with the experiments, we find out the elastic tensor parameters for CoFeB layer. Additionally, we estimate the effective elastic parameters (elastic tensors, Young’s modulus, Poisson’s ratio) of the whole stacks for varying CoFeB thickness. Interestingly, the simulation results, either considering elastic parameters of individual layers or considering effective elastic parameters of whole stacks, show good agreement with the experimental results. These extracted elastic parameters will be very useful to understand the interaction of phonons with other quasiparticles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The surface acoustic waves, i.e., surface phonons may have huge potential for future spintronic devices, if coupled to other waves (e.g., spin waves) or quasiparticles. In order to understand the coupling of acoustic phonons with the spin degree of freedom, especially in magnetic thin film-based heterostructures, one needs to investigate the properties of phonons in those heterostructures. This also allows us to determine the elastic properties of individual magnetic layers and the effective elastic parameters of the whole stacks. Here, we study frequency versus wavevector dispersion of thermally excited SAWs in CoFeB/MgO heterostructures with varying CoFeB thickness by employing Brillouin light spectroscopy. The experimental results are corroborated by finite element method-based simulations. From the best agreement of simulation results with the experiments, we find out the elastic tensor parameters for CoFeB layer. Additionally, we estimate the effective elastic parameters (elastic tensors, Young’s modulus, Poisson’s ratio) of the whole stacks for varying CoFeB thickness. Interestingly, the simulation results, either considering elastic parameters of individual layers or considering effective elastic parameters of whole stacks, show good agreement with the experimental results. These extracted elastic parameters will be very useful to understand the interaction of phonons with other quasiparticles. |
2022 |
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| 58. | Mathieu Moalic, Maciej Krawczyk, Mateusz Zelent Spin-wave spectra in antidot lattice with inhomogeneous perpendicular magnetic anisotropy Journal of Applied Physics, 132 (21), pp. 213901, 2022. @article{doi:10.1063/5.0128621, title = {Spin-wave spectra in antidot lattice with inhomogeneous perpendicular magnetic anisotropy}, author = {Mathieu Moalic and Maciej Krawczyk and Mateusz Zelent}, url = {https://doi.org/10.1063/5.0128621}, doi = {10.1063/5.0128621}, year = {2022}, date = {2022-12-01}, journal = {Journal of Applied Physics}, volume = {132}, number = {21}, pages = {213901}, abstract = {Magnonic crystals are structures with periodically varied magnetic properties that are used to control collective spin-wave excitations. With micromagnetic simulations, we study spin-wave spectra in a 2D antidot lattice based on a multilayered thin film with perpendicular magnetic anisotropy (PMA). We show that the modification of the PMA near the antidot edges introduces interesting changes to the spin-wave spectra, even in a fully saturated state. In particular, the spectra split into two types of excitations: bulk modes with amplitude concentrated in a homogeneous part of the antidot lattice and edge modes with an amplitude localized in the rims of reduced PMA at the antidot edges. Their dependence on the geometrical or material parameters is distinct, but at resonance conditions fulfilled, we found strong hybridization between bulk and radial edge modes. Interestingly, the hybridization between the fundamental modes in bulk and rim is of magnetostatic origin, but the exchange interactions determine the coupling between higher-order radial rim modes and the fundamental bulk mode of the antidot lattice.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnonic crystals are structures with periodically varied magnetic properties that are used to control collective spin-wave excitations. With micromagnetic simulations, we study spin-wave spectra in a 2D antidot lattice based on a multilayered thin film with perpendicular magnetic anisotropy (PMA). We show that the modification of the PMA near the antidot edges introduces interesting changes to the spin-wave spectra, even in a fully saturated state. In particular, the spectra split into two types of excitations: bulk modes with amplitude concentrated in a homogeneous part of the antidot lattice and edge modes with an amplitude localized in the rims of reduced PMA at the antidot edges. Their dependence on the geometrical or material parameters is distinct, but at resonance conditions fulfilled, we found strong hybridization between bulk and radial edge modes. Interestingly, the hybridization between the fundamental modes in bulk and rim is of magnetostatic origin, but the exchange interactions determine the coupling between higher-order radial rim modes and the fundamental bulk mode of the antidot lattice. |
| 57. | Justyna Rychły-Gruszecka, Jakob Walowski, Christian Denker, Tobias Tubandt, Markus Munzenberg, Jarosław W. Kłos Shaping the spin wave spectra of planar 1D magnonic crystals by the geometrical constraints Scientific Reports, 12 (1), pp. 20678, 2022, ISSN: 2045-2322. @article{Rychły-Gruszecka2022, title = {Shaping the spin wave spectra of planar 1D magnonic crystals by the geometrical constraints}, author = {Justyna Rychły-Gruszecka and Jakob Walowski and Christian Denker and Tobias Tubandt and Markus Munzenberg and Jarosław W. Kłos}, url = {https://doi.org/10.1038/s41598-022-24969-x}, doi = {10.1038/s41598-022-24969-x}, issn = {2045-2322}, year = {2022}, date = {2022-11-30}, journal = {Scientific Reports}, volume = {12}, number = {1}, pages = {20678}, abstract = {We present experimental and numerical studies demonstrating the influence of geometrical parameters on the fundamental spin-wave mode in planar 1D magnonic crystals. The investigated magnonic crystals consist of flat stripes separated by air gaps. The adjustment of geometrical parameters allows tailoring of the spin-wave frequencies. The width of stripes and the width of gaps between them affect spin-wave frequencies in two ways. First, directly by geometrical constraints confining the spin waves inside the stripes. Second, indirectly by spin-wave pinning, freeing the spin waves to a different extent on the edges of stripes. Experimentally, the fundamental spin-wave mode frequencies are measured using an all-optical pump-probe time-resolved magneto-optical Kerr-effect setup. Our studies address the problem of spin-wave confinement and spin-wave dipolar pinning in an array of coupled stripes. We show that the frequency of fundamental mode can be tuned to a large extent by adjusting the width of the stripes and the width of gaps between them.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present experimental and numerical studies demonstrating the influence of geometrical parameters on the fundamental spin-wave mode in planar 1D magnonic crystals. The investigated magnonic crystals consist of flat stripes separated by air gaps. The adjustment of geometrical parameters allows tailoring of the spin-wave frequencies. The width of stripes and the width of gaps between them affect spin-wave frequencies in two ways. First, directly by geometrical constraints confining the spin waves inside the stripes. Second, indirectly by spin-wave pinning, freeing the spin waves to a different extent on the edges of stripes. Experimentally, the fundamental spin-wave mode frequencies are measured using an all-optical pump-probe time-resolved magneto-optical Kerr-effect setup. Our studies address the problem of spin-wave confinement and spin-wave dipolar pinning in an array of coupled stripes. We show that the frequency of fundamental mode can be tuned to a large extent by adjusting the width of the stripes and the width of gaps between them. |
| 56. | Andriy E. Serebryannikov, Akhlesh Lakhtakia, Ekmel Ozbay Opt. Mater. Express, 12 (12), pp. 4594–4605, 2022. @article{Serebryannikov:22, title = {Thermally switchable, bifunctional, scalable, mid-infrared metasurfaces with VO2 grids capable of versatile polarization manipulation and asymmetric transmission}, author = {Andriy E. Serebryannikov and Akhlesh Lakhtakia and Ekmel Ozbay}, url = {https://opg.optica.org/ome/abstract.cfm?URI=ome-12-12-4594}, doi = {10.1364/OME.465468}, year = {2022}, date = {2022-11-16}, journal = {Opt. Mater. Express}, volume = {12}, number = {12}, pages = {4594--4605}, publisher = {Optica Publishing Group}, abstract = {We conceptualized three-array scalable bifunctional metasurfaces comprising only three thin strip grids and numerically determined their characteristics in the mid-infrared spectral regime for switchable operation scenarios involving polarization manipulation and related diodelike asymmetric transmission (AT) as one of two functionalities. A few or all of the grids were taken to be made of VO2, a bifunctionality-enabling phase-change material; there are no layers and/or meta-atoms comprising simultaneously both metal and VO2. For each proposed metasurface, two effective structures and, therefore, two different functionalities exist, corresponding to the metallic and insulating phases of VO2. The achieved scenarios of functionality switching significantly depend on the way in which VO2 is incorporated into the metasurface. Switchable bands of polarization manipulation are up to 40 THz wide. The AT band can be modulated when Fabry–Perot (anti-) resonances come into play. Besides, transmission regimes with the cross-polarized component insensitive to VO2 phase change are possible, as well as the ones with all co- and cross-polarized components having the same magnitude for both linear polarizations of the incident wave.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We conceptualized three-array scalable bifunctional metasurfaces comprising only three thin strip grids and numerically determined their characteristics in the mid-infrared spectral regime for switchable operation scenarios involving polarization manipulation and related diodelike asymmetric transmission (AT) as one of two functionalities. A few or all of the grids were taken to be made of VO2, a bifunctionality-enabling phase-change material; there are no layers and/or meta-atoms comprising simultaneously both metal and VO2. For each proposed metasurface, two effective structures and, therefore, two different functionalities exist, corresponding to the metallic and insulating phases of VO2. The achieved scenarios of functionality switching significantly depend on the way in which VO2 is incorporated into the metasurface. Switchable bands of polarization manipulation are up to 40 THz wide. The AT band can be modulated when Fabry–Perot (anti-) resonances come into play. Besides, transmission regimes with the cross-polarized component insensitive to VO2 phase change are possible, as well as the ones with all co- and cross-polarized components having the same magnitude for both linear polarizations of the incident wave. |
| 55. | Mateusz Zelent, Paweł Gruszecki, Mathieu Moalic, Olav Hellwig, Anjan Barman, Maciej Krawczyk Spin dynamics in patterned magnetic multilayers with perpendicular magnetic anisotropy Macedo, Rair (Ed.): 73 , pp. 1-51, Academic Press, 2022, ISSN: 0081-1947. @incollection{ZELENT20221, title = {Spin dynamics in patterned magnetic multilayers with perpendicular magnetic anisotropy}, author = {Mateusz Zelent and Paweł Gruszecki and Mathieu Moalic and Olav Hellwig and Anjan Barman and Maciej Krawczyk}, editor = {Rair Macedo}, url = {https://www.sciencedirect.com/science/article/pii/S0081194722000029}, doi = {https://doi.org/10.1016/bs.ssp.2022.08.002}, issn = {0081-1947}, year = {2022}, date = {2022-10-27}, volume = {73}, pages = {1-51}, publisher = {Academic Press}, series = {Solid State Physics}, abstract = {The magnetization dynamics in nanostructures has been extensively studied in the last decades, and nanomagnetism has evolved significantly over that time, discovering new effects, developing numerous applications, and identifying promising new directions. This includes magnonics, an emerging research field oriented on the study of spin-wave dynamics and their applications. In this context, thin ferromagnetic films with perpendicular magnetic anisotropy (PMA) offer interesting opportunities to study spin waves, in particular, due to out-of-plane magnetization in remanence or at relatively weak external magnetic fields. This is the only magnetization configuration offering isotropic in-plane spin-wave propagation within the sample plane, the forward volume magnetostatic spin-wave geometry. The isotropic dispersion relation is highly important in designing signal-processing devices, offering superior prospects for direct replicating various concepts from photonics into magnonics. Analogous to photonic or phononic crystals, which are the building blocks of optoelectronics and phononics, magnonic crystals are considered as key components in magnonics applications. Arrays of nanodots and structured ferromagnetic thin films with a periodic array of holes, popularly known as antidot lattices based on PMA multilayers, have been recently studied. Novel magnonic properties related to propagating spin-wave modes, exploitation of the band gaps, and confined modes were demonstrated. Also, the existence of nontrivial magnonic band topologies has been shown. Moreover, the combination of PMA and Dzyaloshinskii–Moriya interaction leads to the formation of chiral magnetization states, including Néel domain walls, skyrmions, and skyrmionium states. This promotes the multilayers with PMA as an interesting topic for magnonics and this chapter reviews the background and attempts to provide future perspectives in this research field.}, keywords = {}, pubstate = {published}, tppubtype = {incollection} } The magnetization dynamics in nanostructures has been extensively studied in the last decades, and nanomagnetism has evolved significantly over that time, discovering new effects, developing numerous applications, and identifying promising new directions. This includes magnonics, an emerging research field oriented on the study of spin-wave dynamics and their applications. In this context, thin ferromagnetic films with perpendicular magnetic anisotropy (PMA) offer interesting opportunities to study spin waves, in particular, due to out-of-plane magnetization in remanence or at relatively weak external magnetic fields. This is the only magnetization configuration offering isotropic in-plane spin-wave propagation within the sample plane, the forward volume magnetostatic spin-wave geometry. The isotropic dispersion relation is highly important in designing signal-processing devices, offering superior prospects for direct replicating various concepts from photonics into magnonics. Analogous to photonic or phononic crystals, which are the building blocks of optoelectronics and phononics, magnonic crystals are considered as key components in magnonics applications. Arrays of nanodots and structured ferromagnetic thin films with a periodic array of holes, popularly known as antidot lattices based on PMA multilayers, have been recently studied. Novel magnonic properties related to propagating spin-wave modes, exploitation of the band gaps, and confined modes were demonstrated. Also, the existence of nontrivial magnonic band topologies has been shown. Moreover, the combination of PMA and Dzyaloshinskii–Moriya interaction leads to the formation of chiral magnetization states, including Néel domain walls, skyrmions, and skyrmionium states. This promotes the multilayers with PMA as an interesting topic for magnonics and this chapter reviews the background and attempts to provide future perspectives in this research field. |
| 54. | Aleksey Girich, Liubov Ivzhenko, Artem Hrinchenko, Sergey Tarapov, Oleh Yermakov IEEE Microwave and Wireless Components Letters, pp. 1-4, 2022. @article{9931333, title = {Manipulation Over Surface Waves in Bilayer Hyperbolic Metasurfaces: Topological Transition and Multidirectional Canalization}, author = {Aleksey Girich and Liubov Ivzhenko and Artem Hrinchenko and Sergey Tarapov and Oleh Yermakov}, doi = {10.1109/LMWC.2022.3215016}, year = {2022}, date = {2022-10-27}, journal = {IEEE Microwave and Wireless Components Letters}, pages = {1-4}, abstract = {Spoof surface plasmon-polariton is a type of surface wave (SW) propagating at the artificially engineered structures in microwave and terahertz ranges. These SWs are highly important in planar photonic and on-chip devices, integrated circuits, lenses, sensors, and antennas applications. However, it is still a challenge to control the propagation regime of such SWs including the wavefront shapes and propagation directions. In this letter, we study the SWs in bilayer hyperbolic metasurfaces and show that the interplay between two layers allows them to manage their regime of propagation. We demonstrate the switching between the angle and number of propagation directions of SWs at the same frequency. Finally, we demonstrate experimentally the tunable multidirectional in-plane canalization of SWs by adjusting the directions of their propagation within the angular range from 0 to 12.8 deg. The discovered rotation-mediated interlayer coupling of hyperbolic metasurfaces paves the way toward efficient in-plane transfer of localized electromagnetic signals.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spoof surface plasmon-polariton is a type of surface wave (SW) propagating at the artificially engineered structures in microwave and terahertz ranges. These SWs are highly important in planar photonic and on-chip devices, integrated circuits, lenses, sensors, and antennas applications. However, it is still a challenge to control the propagation regime of such SWs including the wavefront shapes and propagation directions. In this letter, we study the SWs in bilayer hyperbolic metasurfaces and show that the interplay between two layers allows them to manage their regime of propagation. We demonstrate the switching between the angle and number of propagation directions of SWs at the same frequency. Finally, we demonstrate experimentally the tunable multidirectional in-plane canalization of SWs by adjusting the directions of their propagation within the angular range from 0 to 12.8 deg. The discovered rotation-mediated interlayer coupling of hyperbolic metasurfaces paves the way toward efficient in-plane transfer of localized electromagnetic signals. |
| 53. | Tomoyuki Yokouchi, Satoshi Sugimoto, Bivas Rana, Shinichiro Seki, Naoki Ogawa, Yuki Shiomi, Shinya Kasai, Yoshichika Otani Pattern recognition with neuromorphic computing using magnetic field-induced dynamics of skyrmions Science Advances, 8 (39), pp. eabq5652, 2022. @article{doi:10.1126/sciadv.abq5652, title = {Pattern recognition with neuromorphic computing using magnetic field-induced dynamics of skyrmions}, author = {Tomoyuki Yokouchi and Satoshi Sugimoto and Bivas Rana and Shinichiro Seki and Naoki Ogawa and Yuki Shiomi and Shinya Kasai and Yoshichika Otani}, url = {https://www.science.org/doi/pdf/10.1126/sciadv.abq5652}, doi = {10.1126/sciadv.abq5652}, year = {2022}, date = {2022-09-30}, journal = {Science Advances}, volume = {8}, number = {39}, pages = {eabq5652}, abstract = {Nonlinear phenomena in physical systems can be used for brain-inspired computing with low energy consumption. Response from the dynamics of a topological spin structure called skyrmion is one of the candidates for such a neuromorphic computing. However, its ability has not been well explored experimentally. Here, we experimentally demonstrate neuromorphic computing using nonlinear response originating from magnetic field–induced dynamics of skyrmions. We designed a simple-structured skyrmion-based neuromorphic device and succeeded in handwritten digit recognition with the accuracy as large as 94.7% and waveform recognition. Notably, there exists a positive correlation between the recognition accuracy and the number of skyrmions in the devices. The large degrees of freedom of skyrmion systems, such as the position and the size, originate from the more complex nonlinear mapping, the larger output dimension, and, thus, high accuracy. Our results provide a guideline for developing energy-saving and high-performance skyrmion neuromorphic computing devices. Skyrmion-based neuromorphic computing device recognizes waveforms and handwritten digits with high accuracy.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nonlinear phenomena in physical systems can be used for brain-inspired computing with low energy consumption. Response from the dynamics of a topological spin structure called skyrmion is one of the candidates for such a neuromorphic computing. However, its ability has not been well explored experimentally. Here, we experimentally demonstrate neuromorphic computing using nonlinear response originating from magnetic field–induced dynamics of skyrmions. We designed a simple-structured skyrmion-based neuromorphic device and succeeded in handwritten digit recognition with the accuracy as large as 94.7% and waveform recognition. Notably, there exists a positive correlation between the recognition accuracy and the number of skyrmions in the devices. The large degrees of freedom of skyrmion systems, such as the position and the size, originate from the more complex nonlinear mapping, the larger output dimension, and, thus, high accuracy. Our results provide a guideline for developing energy-saving and high-performance skyrmion neuromorphic computing devices. Skyrmion-based neuromorphic computing device recognizes waveforms and handwritten digits with high accuracy. |
| 52. | Krzysztof Sobucki, Maciej Krawczyk, Elena V. Tartakovskaya, Piotr Graczyk Magnon spectrum of Bloch hopfion beyond ferromagnetic resonance APL Materials, 10 (9), pp. 091103, 2022. @article{doi:10.1063/5.0100484, title = {Magnon spectrum of Bloch hopfion beyond ferromagnetic resonance}, author = {Krzysztof Sobucki and Maciej Krawczyk and Elena V. Tartakovskaya and Piotr Graczyk}, url = {https://doi.org/10.1063/5.0100484}, doi = {10.1063/5.0100484}, year = {2022}, date = {2022-09-08}, journal = {APL Materials}, volume = {10}, number = {9}, pages = {091103}, abstract = {With the development of new nanofabrication technologies and measurement techniques, the interest of researchers is moving toward 3D structures and 3D magnetization textures. Special attention is paid to the topological magnetization textures, particularly hopfions. In this paper, we investigate the magnetization dynamics of the hopfion through the numerical solution of the eigenvalue problem. We show that the spectrum of spin-wave modes of the hopfion is much richer than those attainable in ferromagnetic resonance experiments or time-domain simulations reported so far. We identified four groups of modes that differ in the character of oscillations (clockwise or counter-clockwise rotation sense), the position of an average amplitude localization along the radial direction, and different oscillations in the vertical cross section. The knowledge of the full spin-wave spectrum shall help in hopfion identification, understanding of the interaction between spin waves and hopfion dynamics as well as the development of the potential of hopfion in spintronic and magnonic applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } With the development of new nanofabrication technologies and measurement techniques, the interest of researchers is moving toward 3D structures and 3D magnetization textures. Special attention is paid to the topological magnetization textures, particularly hopfions. In this paper, we investigate the magnetization dynamics of the hopfion through the numerical solution of the eigenvalue problem. We show that the spectrum of spin-wave modes of the hopfion is much richer than those attainable in ferromagnetic resonance experiments or time-domain simulations reported so far. We identified four groups of modes that differ in the character of oscillations (clockwise or counter-clockwise rotation sense), the position of an average amplitude localization along the radial direction, and different oscillations in the vertical cross section. The knowledge of the full spin-wave spectrum shall help in hopfion identification, understanding of the interaction between spin waves and hopfion dynamics as well as the development of the potential of hopfion in spintronic and magnonic applications. |
| 51. | Katarzyna Kotus, Mathieu Moalic, Mateusz Zelent, Maciej Krawczyk, Paweł Gruszecki Scattering of spin waves in a multimode waveguide under the influence of confined magnetic skyrmion APL Materials, 10 (9), pp. 091101, 2022. @article{doi:10.1063/5.0100594, title = {Scattering of spin waves in a multimode waveguide under the influence of confined magnetic skyrmion}, author = {Katarzyna Kotus and Mathieu Moalic and Mateusz Zelent and Maciej Krawczyk and Paweł Gruszecki}, url = {https://doi.org/10.1063/5.0100594}, doi = {10.1063/5.0100594}, year = {2022}, date = {2022-09-08}, journal = {APL Materials}, volume = {10}, number = {9}, pages = {091101}, abstract = {Nontrivial magnetization textures, such as skyrmions, have become a driving force in the physics of magnetism. Furthermore, the utilization of magnetization textures is fueling the development of magnon-based technologies that could provide beyond-CMOS solutions. Here, using a self-developed spin wave (SW) excitation scheme, we selectively excite specific modes and investigate the scattering of SWs on nanodot hosting a Néel-type skyrmion and placed above a multimode waveguide. In particular, at low frequencies, we observe significant reflections from the imprint induced by the skyrmion upon the waveguide. As the frequency increases, the transmission increases as well; however, it is accompanied by scattering to other types of modes. Here, we observe a direct contribution of the skyrmion to the scattering process and various types of conversions of the incident SW modes into other modes quantized by width for both reflected and transmitted SWs. The utilization of imprinted magnetization textures in nonplanar systems to control SW flow can open new possibilities for developing SW-based circuits for ultralow-power signal processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nontrivial magnetization textures, such as skyrmions, have become a driving force in the physics of magnetism. Furthermore, the utilization of magnetization textures is fueling the development of magnon-based technologies that could provide beyond-CMOS solutions. Here, using a self-developed spin wave (SW) excitation scheme, we selectively excite specific modes and investigate the scattering of SWs on nanodot hosting a Néel-type skyrmion and placed above a multimode waveguide. In particular, at low frequencies, we observe significant reflections from the imprint induced by the skyrmion upon the waveguide. As the frequency increases, the transmission increases as well; however, it is accompanied by scattering to other types of modes. Here, we observe a direct contribution of the skyrmion to the scattering process and various types of conversions of the incident SW modes into other modes quantized by width for both reflected and transmitted SWs. The utilization of imprinted magnetization textures in nonplanar systems to control SW flow can open new possibilities for developing SW-based circuits for ultralow-power signal processing. |
| 50. | Krzysztof Szulc, Silvia Tacchi, Aurelio Hierro-Rodríguez, Javier Díaz, Paweł Gruszecki, Piotr Graczyk, Carlos Quirós, Daniel Markó, José Ignacio Martín, María Vélez, David S Schmool, Giovanni Carlotti, Maciej Krawczyk, Luis Manuel Álvarez-Prado ACS Nano, 0 (0), pp. 0, 2022, (PMID: 36043881). @article{doi:10.1021/acsnano.2c04256, title = {Reconfigurable Magnonic Crystals Based on Imprinted Magnetization Textures in Hard and Soft Dipolar-Coupled Bilayers}, author = {Krzysztof Szulc and Silvia Tacchi and Aurelio Hierro-Rodríguez and Javier Díaz and Paweł Gruszecki and Piotr Graczyk and Carlos Quirós and Daniel Markó and José Ignacio Martín and María Vélez and David S Schmool and Giovanni Carlotti and Maciej Krawczyk and Luis Manuel Álvarez-Prado}, url = {https://doi.org/10.1021/acsnano.2c04256}, doi = {10.1021/acsnano.2c04256}, year = {2022}, date = {2022-08-31}, journal = {ACS Nano}, volume = {0}, number = {0}, pages = {0}, abstract = {Reconfigurable magnetization textures offer control of spin waves with promising properties for future low-power beyond-CMOS systems. However, materials with perpendicular magnetic anisotropy (PMA) suitable for stable magnetization-texture formation are characterized by high damping, which limits their applicability in magnonic devices. Here, we propose to overcome this limitation by using hybrid structures, i.e., a PMA layer magnetostatically coupled to a low-damping soft ferromagnetic film. We experimentally show that a periodic stripe-domain texture from a PMA layer is imprinted upon the soft layer and induces a nonreciprocal dispersion relation of the spin waves confined to the low-damping film. Moreover, an asymmetric bandgap features the spin-wave band diagram, which is a clear demonstration of collective spin-wave dynamics, a property characteristic for magnonic crystals with broken time-reversal symmetry. The composite character of the hybrid structure allows for stabilization of two magnetic states at remanence, with parallel and antiparallel orientation of net magnetization in hard and soft layers. The states can be switched using a low external magnetic field; therefore, the proposed system obtains an additional functionality of state reconfigurability. This study offers a link between reconfigurable magnetization textures and low-damping spin-wave dynamics, providing an opportunity to create miniaturized, programmable, and energy-efficient signal processing devices operating at high frequencies.}, note = {PMID: 36043881}, keywords = {}, pubstate = {published}, tppubtype = {article} } Reconfigurable magnetization textures offer control of spin waves with promising properties for future low-power beyond-CMOS systems. However, materials with perpendicular magnetic anisotropy (PMA) suitable for stable magnetization-texture formation are characterized by high damping, which limits their applicability in magnonic devices. Here, we propose to overcome this limitation by using hybrid structures, i.e., a PMA layer magnetostatically coupled to a low-damping soft ferromagnetic film. We experimentally show that a periodic stripe-domain texture from a PMA layer is imprinted upon the soft layer and induces a nonreciprocal dispersion relation of the spin waves confined to the low-damping film. Moreover, an asymmetric bandgap features the spin-wave band diagram, which is a clear demonstration of collective spin-wave dynamics, a property characteristic for magnonic crystals with broken time-reversal symmetry. The composite character of the hybrid structure allows for stabilization of two magnetic states at remanence, with parallel and antiparallel orientation of net magnetization in hard and soft layers. The states can be switched using a low external magnetic field; therefore, the proposed system obtains an additional functionality of state reconfigurability. This study offers a link between reconfigurable magnetization textures and low-damping spin-wave dynamics, providing an opportunity to create miniaturized, programmable, and energy-efficient signal processing devices operating at high frequencies. |
| 49. | Szymon Mieszczak, Maciej Krawczyk, Jarosław W. Kłos Spin-wave localization on phasonic defects in a one-dimensional magnonic quasicrystal Phys. Rev. B, 106 , pp. 064430, 2022. @article{PhysRevB.106.064430, title = {Spin-wave localization on phasonic defects in a one-dimensional magnonic quasicrystal}, author = {Szymon Mieszczak and Maciej Krawczyk and Jarosław W. Kłos}, url = {https://link.aps.org/doi/10.1103/PhysRevB.106.064430}, doi = {10.1103/PhysRevB.106.064430}, year = {2022}, date = {2022-08-25}, journal = {Phys. Rev. B}, volume = {106}, pages = {064430}, publisher = {American Physical Society}, abstract = {We report on the evolution of the spin-wave spectrum under structural disorder introduced intentionally into a one-dimensional magnonic quasicrystal. We study theoretically a system composed of ferromagnetic strips arranged in a Fibonacci sequence. We considered several stages of disorder in the form of phasonic defects, where different rearrangements of strips are introduced. By transition from the quasiperiodic order towards disorder, we show a gradual degradation of spin-wave fractal spectra and closing of the frequency gaps. In particular, the phasonic defects lead to the disappearance of the van Hove singularities at the frequency gap edges by moving modes into the frequency gaps and creating new modes inside the frequency gaps. These modes disperse and eventually can close the gap, with increasing disorder levels. The work reveals how the presence of disorder modifies the intrinsic spin-wave localization existing in undefected magnonic quasicrystals. The paper contributes to the knowledge of magnonic Fibonacci quasicrystals and opens the way to study of the phasonic defects in two-dimensional magnonic quasicrystals.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report on the evolution of the spin-wave spectrum under structural disorder introduced intentionally into a one-dimensional magnonic quasicrystal. We study theoretically a system composed of ferromagnetic strips arranged in a Fibonacci sequence. We considered several stages of disorder in the form of phasonic defects, where different rearrangements of strips are introduced. By transition from the quasiperiodic order towards disorder, we show a gradual degradation of spin-wave fractal spectra and closing of the frequency gaps. In particular, the phasonic defects lead to the disappearance of the van Hove singularities at the frequency gap edges by moving modes into the frequency gaps and creating new modes inside the frequency gaps. These modes disperse and eventually can close the gap, with increasing disorder levels. The work reveals how the presence of disorder modifies the intrinsic spin-wave localization existing in undefected magnonic quasicrystals. The paper contributes to the knowledge of magnonic Fibonacci quasicrystals and opens the way to study of the phasonic defects in two-dimensional magnonic quasicrystals. |
| 48. | Mateusz Gołȩbiewski, Paweł Gruszecki, Maciej Krawczyk Self-Imaging of Spin Waves in Thin, Multimode Ferromagnetic Waveguides IEEE Transactions on Magnetics, 58 (8), pp. 1-5, 2022, ISSN: 1941-0069. @article{9668947, title = {Self-Imaging of Spin Waves in Thin, Multimode Ferromagnetic Waveguides}, author = {Mateusz Gołȩbiewski and Paweł Gruszecki and Maciej Krawczyk}, doi = {10.1109/TMAG.2022.3140280}, issn = {1941-0069}, year = {2022}, date = {2022-08-01}, journal = {IEEE Transactions on Magnetics}, volume = {58}, number = {8}, pages = {1-5}, abstract = {Self-imaging of waves is an intriguing and spectacular effect. The phenomenon was first observed for light in 1836 by Henry Fox Talbot and to this day is the subject of research in many areas of physics, for various types of waves and in terms of different applications. This article is a Talbot-effect study for spin waves (SWs) in systems composed of a thin, ferromagnetic waveguide with a series of single-mode sources of SWs flowing into it. The proposed systems are studied with the use of micromagnetic simulations, and the SW self-imaging dependencies on many parameters are examined. We formulated conditions required for the formation of self-images and suitable for experimental realization. The results of the research form the basis for the further development of self-imaging-based magnonic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Self-imaging of waves is an intriguing and spectacular effect. The phenomenon was first observed for light in 1836 by Henry Fox Talbot and to this day is the subject of research in many areas of physics, for various types of waves and in terms of different applications. This article is a Talbot-effect study for spin waves (SWs) in systems composed of a thin, ferromagnetic waveguide with a series of single-mode sources of SWs flowing into it. The proposed systems are studied with the use of micromagnetic simulations, and the SW self-imaging dependencies on many parameters are examined. We formulated conditions required for the formation of self-images and suitable for experimental realization. The results of the research form the basis for the further development of self-imaging-based magnonic devices. |
| 47. | Mateusz Gołębiewski, Paweł Gruszecki, Maciej Krawczyk Self-Imaging Based Programmable Spin-Wave Lookup Tables Advanced Electronic Materials, n/a (n/a), pp. 2200373, 2022. @article{https://doi.org/10.1002/aelm.202200373, title = {Self-Imaging Based Programmable Spin-Wave Lookup Tables}, author = {Mateusz Gołębiewski and Paweł Gruszecki and Maciej Krawczyk}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aelm.202200373}, doi = {https://doi.org/10.1002/aelm.202200373}, year = {2022}, date = {2022-07-21}, journal = {Advanced Electronic Materials}, volume = {n/a}, number = {n/a}, pages = {2200373}, abstract = {Abstract Inclusion of spin waves into the computing paradigm, where complementary metal-oxide-semiconductor devices are still at the fore, is now a challenge for scientists around the world. In this work, a wave phenomenon that has not yet been used in magnonics-self-imaging, also known as the Talbot effect, to design and simulate the operation of interference systems that perform logic functions on spin waves in thin ferromagnetic multimode waveguides is utilized. Lookup tables operating in this way are characterized by high programmability and scalability; thanks to which they are promising for their implementation in field-programmable gate arrays circuits, where multiple logic realizations can be obtained.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Abstract Inclusion of spin waves into the computing paradigm, where complementary metal-oxide-semiconductor devices are still at the fore, is now a challenge for scientists around the world. In this work, a wave phenomenon that has not yet been used in magnonics-self-imaging, also known as the Talbot effect, to design and simulate the operation of interference systems that perform logic functions on spin waves in thin ferromagnetic multimode waveguides is utilized. Lookup tables operating in this way are characterized by high programmability and scalability; thanks to which they are promising for their implementation in field-programmable gate arrays circuits, where multiple logic realizations can be obtained. |
| 46. | Szymon Mieszczak, Jarosław W. Kłos Interface modes in planar one-dimensional magnonic crystals Scientific Reports, 12 (1), pp. 11335, 2022, ISSN: 2045-2322. @article{mieszczak_interface_2022, title = {Interface modes in planar one-dimensional magnonic crystals}, author = {Szymon Mieszczak and Jarosław W. Kłos}, url = {https://www.nature.com/articles/s41598-022-15328-x}, doi = {10.1038/s41598-022-15328-x}, issn = {2045-2322}, year = {2022}, date = {2022-07-05}, urldate = {2022-07-11}, journal = {Scientific Reports}, volume = {12}, number = {1}, pages = {11335}, abstract = {We present the concept of Zak phase for spin waves in planar magnonic crystals and discuss the existence condition of interface modes localized on the boundary between two magnonic crystals with centrosymmetric unit cells. Using the symmetry criterion and analyzing the logarithmic derivative of the Bloch function, we study the interface modes and demonstrate the bulk-to-edge correspondence. Our theoretical results are verified numerically and extended to the case in which one of the magnonic crystals has a non-centrosymmetric unit cells. We show that by shifting the unit cell, the interface modes can traverse between the band gap edges. Our work also investigate the role of the dipolar interaction, by comparison the systems both with exchange interaction only and combined dipolar-exchange interactions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present the concept of Zak phase for spin waves in planar magnonic crystals and discuss the existence condition of interface modes localized on the boundary between two magnonic crystals with centrosymmetric unit cells. Using the symmetry criterion and analyzing the logarithmic derivative of the Bloch function, we study the interface modes and demonstrate the bulk-to-edge correspondence. Our theoretical results are verified numerically and extended to the case in which one of the magnonic crystals has a non-centrosymmetric unit cells. We show that by shifting the unit cell, the interface modes can traverse between the band gap edges. Our work also investigate the role of the dipolar interaction, by comparison the systems both with exchange interaction only and combined dipolar-exchange interactions. |
| 45. | Surya Narayan Panda, Bivas Rana, YoshiChika Otani, Anjan Barman Role of Spin–Orbit Coupling on Ultrafast Spin Dynamics in Nonmagnet/Ferromagnet Heterostructures Advanced Quantum Technologies, 2022 , pp. 2200016, 2022. @article{https://doi.org/10.1002/qute.202200016, title = {Role of Spin–Orbit Coupling on Ultrafast Spin Dynamics in Nonmagnet/Ferromagnet Heterostructures}, author = {Surya Narayan Panda and Bivas Rana and YoshiChika Otani and Anjan Barman}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/qute.202200016}, doi = {https://doi.org/10.1002/qute.202200016}, year = {2022}, date = {2022-07-01}, journal = {Advanced Quantum Technologies}, volume = {2022}, pages = {2200016}, abstract = {Abstract Spin–orbit coupling (SOC), the interaction between spin and orbital angular momentum of electrons, is imperative to control magnetic properties of nonmagnet (NM)/ferromagnet (FM) heterostructures and design energy-efficient and faster spin-based devices. Here, femtosecond pulsed laser-induced time-resolved magneto-optical Kerr effect magnetometry is employed to investigate magnetization dynamics in different NM/Co20Fe60B20 heterostructures, where the NM layer varies as Cu, Ta, W, Pt, Ta/Ru/Ta, and Si/SiO2 (no underlayer) that differ in SOC strength. It is observed that there is a systematic variation in ultrafast demagnetization time (τm), fast remagnetization time (τr), and Gilbert damping parameter (α) with the SOC strength of the underlayer and an inverse relationship between α and τm, τr is established due to the dominant contribution of spin current transport in ultrafast demagnetization and fast remagnetization processes. The spin pumping formalism estimates the effective spin-mixing conductance (Geff) for different interfaces, which signifies that the high SOC strength of underlayers results in high Geff indicating more efficient transport of spin current through it. This study suggests that the SOC strength of the NM underlayer plays a significant role in controlling the ultrafast demagnetization process through interfacial spin current transport in a NM/FM heterostructure which can be beneficial for the development of ultrafast spintronics devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Abstract Spin–orbit coupling (SOC), the interaction between spin and orbital angular momentum of electrons, is imperative to control magnetic properties of nonmagnet (NM)/ferromagnet (FM) heterostructures and design energy-efficient and faster spin-based devices. Here, femtosecond pulsed laser-induced time-resolved magneto-optical Kerr effect magnetometry is employed to investigate magnetization dynamics in different NM/Co20Fe60B20 heterostructures, where the NM layer varies as Cu, Ta, W, Pt, Ta/Ru/Ta, and Si/SiO2 (no underlayer) that differ in SOC strength. It is observed that there is a systematic variation in ultrafast demagnetization time (τm), fast remagnetization time (τr), and Gilbert damping parameter (α) with the SOC strength of the underlayer and an inverse relationship between α and τm, τr is established due to the dominant contribution of spin current transport in ultrafast demagnetization and fast remagnetization processes. The spin pumping formalism estimates the effective spin-mixing conductance (Geff) for different interfaces, which signifies that the high SOC strength of underlayers results in high Geff indicating more efficient transport of spin current through it. This study suggests that the SOC strength of the NM underlayer plays a significant role in controlling the ultrafast demagnetization process through interfacial spin current transport in a NM/FM heterostructure which can be beneficial for the development of ultrafast spintronics devices. |
| 44. | M Szafrański, Zbigniew Tylczyński, M Wiesner, P Czarnecki, V V Ghazaryan, A M Petrosyan Materials & Design, 220 , pp. 110893, 2022, ISSN: 0264-1275. @article{SZAFRANSKI2022110893, title = {Above-room-temperature ferroelectricity and piezoelectric activity of dimethylglycinium-dimethylglycine chloride}, author = {M Szafrański and Zbigniew Tylczyński and M Wiesner and P Czarnecki and V V Ghazaryan and A M Petrosyan}, url = {https://www.sciencedirect.com/science/article/pii/S0264127522005159}, doi = {https://doi.org/10.1016/j.matdes.2022.110893}, issn = {0264-1275}, year = {2022}, date = {2022-06-27}, journal = {Materials & Design}, volume = {220}, pages = {110893}, abstract = {Heavy-metal-free ferroelectrics are sought as environmentally compatible alternatives to commonly used inorganic oxides. Here, we demonstrate direct evidence of the ferroelectric properties of a hybrid organic–inorganic material, dimethylglycinium-dimethylglycine chloride. At room temperature, the compound crystallizes in the polar space group P21 and exhibits a switchable spontaneous polarization of 1.9 μC cm−2. Ferroelectric properties are preserved in a wide temperature range up to about 401 K, where the crystal undergoes the transition to the paraelectric phase of the space group P21/c. The temperature-dependent single-crystal X-ray diffraction study and the calorimetric data indicate an order–disorder contribution to the transition mechanism, which is consistent with the critical slowing down of the dielectric relaxation observed near the Curie point. The spontaneous polarization results from ionic displacements that are induced by changes in the disordering of the dimeric cations. In the ferroelectric phase, the crystal exhibits remarkable piezoelectric activity. The electromechanical and elastic properties of the material were thoroughly characterized.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Heavy-metal-free ferroelectrics are sought as environmentally compatible alternatives to commonly used inorganic oxides. Here, we demonstrate direct evidence of the ferroelectric properties of a hybrid organic–inorganic material, dimethylglycinium-dimethylglycine chloride. At room temperature, the compound crystallizes in the polar space group P21 and exhibits a switchable spontaneous polarization of 1.9 μC cm−2. Ferroelectric properties are preserved in a wide temperature range up to about 401 K, where the crystal undergoes the transition to the paraelectric phase of the space group P21/c. The temperature-dependent single-crystal X-ray diffraction study and the calorimetric data indicate an order–disorder contribution to the transition mechanism, which is consistent with the critical slowing down of the dielectric relaxation observed near the Curie point. The spontaneous polarization results from ionic displacements that are induced by changes in the disordering of the dimeric cations. In the ferroelectric phase, the crystal exhibits remarkable piezoelectric activity. The electromechanical and elastic properties of the material were thoroughly characterized. |
| 43. | Andriy E. Serebryannikov, Diana C Skigin, Guy A E Vandenbosch, Ekmel Ozbay Journal of Applied Physics, 131 (22), pp. 223101, 2022. @article{doi:10.1063/5.0093989, title = {Multifunctional blazed gratings for multiband spatial filtering, retroreflection, splitting, and demultiplexing based on C2 symmetric photonic crystals}, author = {Andriy E. Serebryannikov and Diana C Skigin and Guy A E Vandenbosch and Ekmel Ozbay}, url = {https://doi.org/10.1063/5.0093989}, doi = {10.1063/5.0093989}, year = {2022}, date = {2022-06-08}, journal = {Journal of Applied Physics}, volume = {131}, number = {22}, pages = {223101}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 42. | Aleksandra Trzaskowska, Sławomir Mielcarek, Tomasz Lehmann, Ewa Pruszyńska-Oszmałek, Paweł Kołodziejski, Maciej Głowacki Mechanical properties of the mouse femur after treatment with diclofenac and running exercises Acta of Bioengineering and Biomechanics, 24 (2), pp. null, 2022. @article{TrzaskowskaMechanical2022, title = {Mechanical properties of the mouse femur after treatment with diclofenac and running exercises}, author = {Aleksandra Trzaskowska and Sławomir Mielcarek and Tomasz Lehmann and Ewa Pruszyńska-Oszmałek and Paweł Kołodziejski and Maciej Głowacki}, url = {https://www.actabio.pwr.wroc.pl/Vol24No2/33.pdf}, doi = {10.37190/abb-02061-2022-03}, year = {2022}, date = {2022-05-26}, journal = {Acta of Bioengineering and Biomechanics}, volume = {24}, number = {2}, pages = {null}, abstract = {The flexible properties of the bone are essential for the movement and protection of vital organs. The ability of a bone to resist fractures under the influence of large muscles and physical activity depends on its established mechanical properties. This article discusses how exercise such as treadmill running and taking non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac, affect the musculoskeletal system by modifying the elastic and thermal properties of the left femur of a mouse. Methods: The research was conducted using 9-week-old C57BL/6J female mice. In order to investigate the elastic and thermal properties of bones, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) were performed. Results: The study of elastic properties, followed by in-depth statistical analysis, shows that taking diclofenac slightly reduces the elastic parameters of the bones under study. These changes are more pronounced in DSC studies, the shift of the observed endothermic peaks is on the order of several degrees with a simultaneous increase in the enthalpy of this process. Conclusions: The opposite effect of the applied factors – diclofenac and running – on the elastic properties of the bones of the examined mice was found. The external factors – running and diclofenac – modify the basic parameters of the endothermic process associated with the release of water.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The flexible properties of the bone are essential for the movement and protection of vital organs. The ability of a bone to resist fractures under the influence of large muscles and physical activity depends on its established mechanical properties. This article discusses how exercise such as treadmill running and taking non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac, affect the musculoskeletal system by modifying the elastic and thermal properties of the left femur of a mouse. Methods: The research was conducted using 9-week-old C57BL/6J female mice. In order to investigate the elastic and thermal properties of bones, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) were performed. Results: The study of elastic properties, followed by in-depth statistical analysis, shows that taking diclofenac slightly reduces the elastic parameters of the bones under study. These changes are more pronounced in DSC studies, the shift of the observed endothermic peaks is on the order of several degrees with a simultaneous increase in the enthalpy of this process. Conclusions: The opposite effect of the applied factors – diclofenac and running – on the elastic properties of the bones of the examined mice was found. The external factors – running and diclofenac – modify the basic parameters of the endothermic process associated with the release of water. |
| 41. | Angshuman Deka, Bivas Rana, Ryo Anami, Katsuya Miura, Hiromasa Takahashi, YoshiChika Otani, Yasuhiro Fukuma Electric field induced parametric excitation of exchange magnons in a CoFeB/MgO junction Phys. Rev. Research, 4 , pp. 023139, 2022. @article{PhysRevResearch.4.023139, title = {Electric field induced parametric excitation of exchange magnons in a CoFeB/MgO junction}, author = {Angshuman Deka and Bivas Rana and Ryo Anami and Katsuya Miura and Hiromasa Takahashi and YoshiChika Otani and Yasuhiro Fukuma}, url = {https://link.aps.org/doi/10.1103/PhysRevResearch.4.023139}, doi = {10.1103/PhysRevResearch.4.023139}, year = {2022}, date = {2022-05-20}, journal = {Phys. Rev. Research}, volume = {4}, pages = {023139}, publisher = {American Physical Society}, abstract = {Inspired by the success of field-effect transistors in electronics, electric field controlled magnetization dynamics has emerged as an important integrant in low-power spintronic devices. Here, we demonstrate electric field induced parametric excitation for CoFeB/MgO junctions by using interfacial in-plane magnetic anisotropy (IMA). When the IMA and the external magnetic field are parallel to each other, magnons are efficiently excited by electric field induced parametric resonance. The corresponding wavelengths are estimated to be tuned down to exchange interaction length scales by changing the input power and frequency of the applied voltage. A generalized phenomenological model is developed to explain the underlying role of the electric field torque. Electric field control of IMA is shown to be the origin for excitation of both uniform and parametric resonance modes in the in-plane magnetized sample, a crucial element for purely electric field induced magnetization dynamics. Electric field excitation of exchange magnons, with no Joule heating, offers a good opportunity for developing nanoscale magnonic devices and exploring various nonlinear dynamics in nanomagnetic systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Inspired by the success of field-effect transistors in electronics, electric field controlled magnetization dynamics has emerged as an important integrant in low-power spintronic devices. Here, we demonstrate electric field induced parametric excitation for CoFeB/MgO junctions by using interfacial in-plane magnetic anisotropy (IMA). When the IMA and the external magnetic field are parallel to each other, magnons are efficiently excited by electric field induced parametric resonance. The corresponding wavelengths are estimated to be tuned down to exchange interaction length scales by changing the input power and frequency of the applied voltage. A generalized phenomenological model is developed to explain the underlying role of the electric field torque. Electric field control of IMA is shown to be the origin for excitation of both uniform and parametric resonance modes in the in-plane magnetized sample, a crucial element for purely electric field induced magnetization dynamics. Electric field excitation of exchange magnons, with no Joule heating, offers a good opportunity for developing nanoscale magnonic devices and exploring various nonlinear dynamics in nanomagnetic systems. |
| 40. | Jingyuan Zhou, Mateusz Zelent, Zhaochu Luo, Valerio Scagnoli, Maciej Krawczyk, Laura J Heyderman, Susmita Saha Phys. Rev. B, 105 , pp. 174415, 2022. @article{PhysRevB.105.174415, title = {Precessional dynamics of geometrically scaled magnetostatic spin waves in two-dimensional magnonic fractals}, author = {Jingyuan Zhou and Mateusz Zelent and Zhaochu Luo and Valerio Scagnoli and Maciej Krawczyk and Laura J Heyderman and Susmita Saha}, url = {https://link.aps.org/doi/10.1103/PhysRevB.105.174415}, doi = {10.1103/PhysRevB.105.174415}, year = {2022}, date = {2022-05-13}, journal = {Phys. Rev. B}, volume = {105}, pages = {174415}, publisher = {American Physical Society}, abstract = {The control of spin waves in periodic magnetic structures has facilitated the realization of many functional magnonic devices, such as band stop filters and magnonic transistors, where the geometry of the crystal structure plays an important role. Here, we report on the magnetostatic mode formation in an artificial magnetic structure, going beyond the crystal geometry to a fractal structure, where the mode formation is related to the geometric scaling of the fractal structure. Specifically, the precessional dynamics was measured in samples with structures going from simple geometric structures toward a Sierpinski carpet and a Sierpinski triangle. The experimentally observed evolution of the precessional motion could be linked to the progression in the geometric structures that results in a modification of the demagnetizing field. Furthermore, we have found sets of modes at the ferromagnetic resonance frequency that form a scaled spatial distribution following the geometric scaling. Based on this, we have determined the two conditions for such mode formation to occur. One condition is that the associated magnetic boundaries must scale accordingly, and the other condition is that the region where the mode occurs must not coincide with the regions for the edge modes. This established relationship between the fractal geometry and the mode formation in magnetic fractals provides guiding principles for their use in magnonics applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The control of spin waves in periodic magnetic structures has facilitated the realization of many functional magnonic devices, such as band stop filters and magnonic transistors, where the geometry of the crystal structure plays an important role. Here, we report on the magnetostatic mode formation in an artificial magnetic structure, going beyond the crystal geometry to a fractal structure, where the mode formation is related to the geometric scaling of the fractal structure. Specifically, the precessional dynamics was measured in samples with structures going from simple geometric structures toward a Sierpinski carpet and a Sierpinski triangle. The experimentally observed evolution of the precessional motion could be linked to the progression in the geometric structures that results in a modification of the demagnetizing field. Furthermore, we have found sets of modes at the ferromagnetic resonance frequency that form a scaled spatial distribution following the geometric scaling. Based on this, we have determined the two conditions for such mode formation to occur. One condition is that the associated magnetic boundaries must scale accordingly, and the other condition is that the region where the mode occurs must not coincide with the regions for the edge modes. This established relationship between the fractal geometry and the mode formation in magnetic fractals provides guiding principles for their use in magnonics applications. |
| 39. | Paweł Gruszecki, Konstantin Y Guslienko, Igor L Lyubchanskii, Maciej Krawczyk Inelastic Spin-Wave Beam Scattering by Edge-Localized Spin Waves in a Ferromagnetic Thin Film Phys. Rev. Applied, 17 , pp. 044038, 2022. @article{PhysRevApplied.17.044038, title = {Inelastic Spin-Wave Beam Scattering by Edge-Localized Spin Waves in a Ferromagnetic Thin Film}, author = {Paweł Gruszecki and Konstantin Y Guslienko and Igor L Lyubchanskii and Maciej Krawczyk}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.17.044038}, doi = {10.1103/PhysRevApplied.17.044038}, year = {2022}, date = {2022-04-20}, journal = {Phys. Rev. Applied}, volume = {17}, pages = {044038}, publisher = {American Physical Society}, abstract = {Spin waves are promising chargeless information carriers for the future, energetically efficient beyond CMOS systems. Among many advantages are the ease of achieving nonlinearity, the variety of possible interactions, and excitation types. Although the rapidly developing magnonic research has already yielded impressive realizations, multimode nonlinear effects, particularly with propagating waves and their nanoscale realizations, are still an open research problem.We theoretically study the dynamic interactions of spin waves confined to the edge of a thin ferromagnetic film with the spin-wave beam incident at this edge. We find inelastically scattered spin-wave beams at frequencies increased and decreased by the frequency of the edge spin-wave relative to the specularly reflected beam. We observe a strong dependence of the angular shift of the inelastic scattered spin-wave beam on the edge-mode frequency, which allows us to propose a magnonic demultiplexing of the signal encoded in spin waves propagating along the edge. Since dynamic magnetostatic interactions, which are ubiquitous in the spin-wave dynamics, are decisive in this process, this indicates the possibility of implementing the presented effects in other configurations and their use in magnonic systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spin waves are promising chargeless information carriers for the future, energetically efficient beyond CMOS systems. Among many advantages are the ease of achieving nonlinearity, the variety of possible interactions, and excitation types. Although the rapidly developing magnonic research has already yielded impressive realizations, multimode nonlinear effects, particularly with propagating waves and their nanoscale realizations, are still an open research problem.We theoretically study the dynamic interactions of spin waves confined to the edge of a thin ferromagnetic film with the spin-wave beam incident at this edge. We find inelastically scattered spin-wave beams at frequencies increased and decreased by the frequency of the edge spin-wave relative to the specularly reflected beam. We observe a strong dependence of the angular shift of the inelastic scattered spin-wave beam on the edge-mode frequency, which allows us to propose a magnonic demultiplexing of the signal encoded in spin waves propagating along the edge. Since dynamic magnetostatic interactions, which are ubiquitous in the spin-wave dynamics, are decisive in this process, this indicates the possibility of implementing the presented effects in other configurations and their use in magnonic systems. |
| 38. | A K Dhiman, R Gieniusz, Paweł Gruszecki, J Kisielewski, M Matczak, Z Kurant, I Sveklo, U Guzowska, M Tekielak, F Stobiecki, A Maziewski Magnetization statics and dynamics in (Ir/Co/Pt)6 multilayers with Dzyaloshinskii–Moriya interaction AIP Advances, 12 (4), pp. 045007, 2022. @article{Dhiman2022DMI, title = {Magnetization statics and dynamics in (Ir/Co/Pt)6 multilayers with Dzyaloshinskii–Moriya interaction}, author = {A K Dhiman and R Gieniusz and Paweł Gruszecki and J Kisielewski and M Matczak and Z Kurant and I Sveklo and U Guzowska and M Tekielak and F Stobiecki and A Maziewski}, doi = {https://doi.org/10.1063/9.0000339}, year = {2022}, date = {2022-04-04}, urldate = {2022-04-04}, journal = {AIP Advances}, volume = {12}, number = {4}, pages = {045007}, abstract = {Magnetic multilayers of (Ir/Co/Pt)6 with interfacial Dzyaloshinskii-Moriya interaction (IDMI) were deposited by magnetron sputtering with Co thickness d=1.8 nm. Exploiting magneto-optical Kerr effect in longitudinal mode microscopy, magnetic force microscopy, and vibrating sample magnetometry, the magnetic field-driven evolution of domain structures and magnetization hysteresis loops have been studied. The existence of weak stripe domains structure was deduced – tens micrometers size domains with in-plane “core” magnetization modulated by hundred of nanometers domains with out-of-plane magnetization. Micromagnetic simulations interpreted such magnetization distribution. Quantitative evaluation of IDMI was carried out using Brillouin light scattering (BLS) spectroscopy as the difference between Stokes and anti-Stokes peak frequencies Δf. Due to the additive nature of IDMI, the asymmetric combination of Ir and Pt covers led to large values of effective IDMI energy density Deff. It was found that Stokes and anti-Stokes frequencies as well as Δf, measured as a function of in-plane applied magnetic field, show hysteresis. These results are explained under the consideration of the influence of IDMI on the dynamics of the in-plane magnetized “core” with weak stripe domains}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnetic multilayers of (Ir/Co/Pt)6 with interfacial Dzyaloshinskii-Moriya interaction (IDMI) were deposited by magnetron sputtering with Co thickness d=1.8 nm. Exploiting magneto-optical Kerr effect in longitudinal mode microscopy, magnetic force microscopy, and vibrating sample magnetometry, the magnetic field-driven evolution of domain structures and magnetization hysteresis loops have been studied. The existence of weak stripe domains structure was deduced – tens micrometers size domains with in-plane “core” magnetization modulated by hundred of nanometers domains with out-of-plane magnetization. Micromagnetic simulations interpreted such magnetization distribution. Quantitative evaluation of IDMI was carried out using Brillouin light scattering (BLS) spectroscopy as the difference between Stokes and anti-Stokes peak frequencies Δf. Due to the additive nature of IDMI, the asymmetric combination of Ir and Pt covers led to large values of effective IDMI energy density Deff. It was found that Stokes and anti-Stokes frequencies as well as Δf, measured as a function of in-plane applied magnetic field, show hysteresis. These results are explained under the consideration of the influence of IDMI on the dynamics of the in-plane magnetized “core” with weak stripe domains |
| 37. | M Baranowski, Sławomir Mamica Resonance modes of periodically structuralized microwave magnetic elements Journal of Magnetism and Magnetic Materials, 553 , pp. 169261, 2022, ISSN: 0304-8853. @article{BARANOWSKI2022169261, title = {Resonance modes of periodically structuralized microwave magnetic elements}, author = {M Baranowski and Sławomir Mamica}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322002128}, doi = {https://doi.org/10.1016/j.jmmm.2022.169261}, issn = {0304-8853}, year = {2022}, date = {2022-03-16}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {553}, pages = {169261}, abstract = {Here we consider a flower-like structure of a resonator consisting of six elliptical elements, referred to as petals, made from a magnetic material. The petals are positioned with their centres at the corners of a regular hexagon. Using numerical simulations (CST Studio) we examine the effect of different radial orientations of petals. We study resonance modes with a specific distribution of the electromagnetic field within the resonator as well as the effect of the rotation of petals on the field distribution. The mode character is crucial to understand the behaviour of the frequency spectrum. E.g., the rotation of petals influences significantly the frequency of the lowest mode only, while the other frequencies are almost unchanged and this effect is directly related to the profiles of modes. The system studied is a promising candidate for a tuneable component of an integrated detection system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Here we consider a flower-like structure of a resonator consisting of six elliptical elements, referred to as petals, made from a magnetic material. The petals are positioned with their centres at the corners of a regular hexagon. Using numerical simulations (CST Studio) we examine the effect of different radial orientations of petals. We study resonance modes with a specific distribution of the electromagnetic field within the resonator as well as the effect of the rotation of petals on the field distribution. The mode character is crucial to understand the behaviour of the frequency spectrum. E.g., the rotation of petals influences significantly the frequency of the lowest mode only, while the other frequencies are almost unchanged and this effect is directly related to the profiles of modes. The system studied is a promising candidate for a tuneable component of an integrated detection system. |
| 36. | Andriy E. Serebryannikov, Akhlesh Lakhtakia, Guy A E Vandenbosch, Ekmel Ozbay Scientific Reports, 12 (1), pp. 3518, 2022, ISSN: 2045-2322. @article{Serebryannikov2022, title = {Transmissive terahertz metasurfaces with vanadium dioxide split-rings and grids for switchable asymmetric polarization manipulation}, author = {Andriy E. Serebryannikov and Akhlesh Lakhtakia and Guy A E Vandenbosch and Ekmel Ozbay}, url = {https://doi.org/10.1038/s41598-022-07265-6}, doi = {10.1038/s41598-022-07265-6}, issn = {2045-2322}, year = {2022}, date = {2022-03-03}, journal = {Scientific Reports}, volume = {12}, number = {1}, pages = {3518}, abstract = {Metasurfaces containing arrays of thermally tunable metal-free (double-)split-ring meta-atoms and metal-free grids made of vanadium dioxide (VO$$_2$$), a phase-change material can deliver switching between (1) polarization manipulation in transmission mode as well as related asymmetric transmission and (2) other functionalities in the terahertz regime, especially when operation in the transmission mode is needed to be conserved for both phases of VO$$_2$$. As the meta-atom arrays function as arrays of metallic subwavelength resonators for the metallic phase of VO$$_2$$, but as transmissive phase screens for the insulator phase of VO$$_2$$, numerical simulations of double- and triple-array metasurfaces strongly indicate extreme scenarios of functionality switching also when the resulting structure comprises only VO$$_2$$ meta-atoms and VO$$_2$$ grids. More switching scenarios are achievable when only one meta-atom array or one grid is made of VO$$_2$$ components. They are enabled by the efficient coupling of the geometrically identical resonator arrays/grids that are made of the materials that strongly differ in terms of conductivity, i.e. Cu and VO$$_2$$ in the metallic phase.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metasurfaces containing arrays of thermally tunable metal-free (double-)split-ring meta-atoms and metal-free grids made of vanadium dioxide (VO$$_2$$), a phase-change material can deliver switching between (1) polarization manipulation in transmission mode as well as related asymmetric transmission and (2) other functionalities in the terahertz regime, especially when operation in the transmission mode is needed to be conserved for both phases of VO$$_2$$. As the meta-atom arrays function as arrays of metallic subwavelength resonators for the metallic phase of VO$$_2$$, but as transmissive phase screens for the insulator phase of VO$$_2$$, numerical simulations of double- and triple-array metasurfaces strongly indicate extreme scenarios of functionality switching also when the resulting structure comprises only VO$$_2$$ meta-atoms and VO$$_2$$ grids. More switching scenarios are achievable when only one meta-atom array or one grid is made of VO$$_2$$ components. They are enabled by the efficient coupling of the geometrically identical resonator arrays/grids that are made of the materials that strongly differ in terms of conductivity, i.e. Cu and VO$$_2$$ in the metallic phase. |
| 35. | Dominika Kuźma, Łukasz Laskowski, Jarosław W. Kłos, Piotr Zieliński Effects of shape on magnetization switching in systems of magnetic elongated nanoparticles J. Magn. Magn. Mat., 545 , pp. 168685, 2022, ISSN: 0304-8853. @article{KUZMA2022168685, title = {Effects of shape on magnetization switching in systems of magnetic elongated nanoparticles}, author = {Dominika Kuźma and Łukasz Laskowski and Jarosław W. Kłos and Piotr Zieliński}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009215}, doi = {https://doi.org/10.1016/j.jmmm.2021.168685}, issn = {0304-8853}, year = {2022}, date = {2022-03-01}, journal = {J. Magn. Magn. Mat.}, volume = {545}, pages = {168685}, abstract = {The equilibrium magnetization of flat elongated magnetic nanoparticles of different shapes has been determined for a range of the static magnetic fields applied parallel to their long/easy axes. The behaviour of single particles has been compared with that of equidistant chains composed of the same particles. The shapes sharpened at the ends, i.e. elongated diamonds and two-sided swords, switch with minimal inhomogeneities of magnetization and with well rectangular hystereses. This may be useful in designing of binary memory devices. The narrowest hysteresis has been found for hourglass shapes, where the switching is preceded with inhomogeneities of magnetization so the hystereses are rounded. The shapes endowed with broadened heads, such as dumbbells and bones, show vortex-like inhomogeneities, marked with an interesting interplay of helicities, which result in a multi-stage switching with relatively large coercive fields.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The equilibrium magnetization of flat elongated magnetic nanoparticles of different shapes has been determined for a range of the static magnetic fields applied parallel to their long/easy axes. The behaviour of single particles has been compared with that of equidistant chains composed of the same particles. The shapes sharpened at the ends, i.e. elongated diamonds and two-sided swords, switch with minimal inhomogeneities of magnetization and with well rectangular hystereses. This may be useful in designing of binary memory devices. The narrowest hysteresis has been found for hourglass shapes, where the switching is preceded with inhomogeneities of magnetization so the hystereses are rounded. The shapes endowed with broadened heads, such as dumbbells and bones, show vortex-like inhomogeneities, marked with an interesting interplay of helicities, which result in a multi-stage switching with relatively large coercive fields. |
| 34. | Yuliya S Dadoenkova, Maciej Krawczyk, Igor L Lyubchanskii Opt. Mater. Express, 12 (2), pp. 717–726, 2022. @article{Dadoenkova:22, title = {Goos-Hoenchen shift at Brillouin light scattering by a magnetostatic wave in the Damon-Eshbach configuration [Invited]}, author = {Yuliya S Dadoenkova and Maciej Krawczyk and Igor L Lyubchanskii}, url = {http://opg.optica.org/ome/abstract.cfm?URI=ome-12-2-717}, doi = {10.1364/OME.447984}, year = {2022}, date = {2022-02-12}, journal = {Opt. Mater. Express}, volume = {12}, number = {2}, pages = {717--726}, publisher = {OSA}, abstract = {The lateral shift of an optical beam undergoing Brillouin light scattering by a spin wave propagating along the interface between magnetic and dielectric media (Damon-Eshbach configuration) in the total internal reflection geometry is studied theoretically. Linear and quadratic magneto-optic terms in polarization are taken into account. It is shown that the lateral shift depends on the polarization (s- or p-) state of the scattered electromagnetic wave as well as on the frequency of the spin wave.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lateral shift of an optical beam undergoing Brillouin light scattering by a spin wave propagating along the interface between magnetic and dielectric media (Damon-Eshbach configuration) in the total internal reflection geometry is studied theoretically. Linear and quadratic magneto-optic terms in polarization are taken into account. It is shown that the lateral shift depends on the polarization (s- or p-) state of the scattered electromagnetic wave as well as on the frequency of the spin wave. |
| 33. | A V Chumak, P Kabos, M Wu, C Abert, C Adelmann, A O Adeyeye, J Akerman, F G Aliev, A Anane, A Awad, C H Back, A Barman, G E W Bauer, M Becherer, E N Beginin, V A S V Bittencourt, Y M Blanter, P Bortolotti, I Boventer, D A Bozhko, S A Bunyaev, J J Carmiggelt, R R Cheenikundil, F Ciubotaru, S Cotofana, G Csaba, O V Dobrovolskiy, C Dubs, M Elyasi, K G Fripp, H Fulara, I A Golovchanskiy, C Gonzalez-Ballestero, Piotr Graczyk, D Grundler, Paweł Gruszecki, G Gubbiotti, K Guslienko, A Haldar, S Hamdioui, R Hertel, B Hillebrands, T Hioki, A Houshang, C -M Hu, H Huebl, M Huth, E Iacocca, M B Jungfleisch, G N Kakazei, A Khitun, R Khymyn, T Kikkawa, M Kloui, O Klein, Jarosław W. Kłos, S Knauer, S Koraltan, M Kostylev, Maciej Krawczyk, I N Krivorotov, V V Kruglyak, D Lachance-Quirion, S Ladak, R Lebrun, Y Li, M Lindner, R Macedo, S Mayr, G A Melkov, Szymon Mieszczak, Y Nakamura, H T Nembach, A A Nikitin, S A Nikitov, V Novosad, J A Otalora, Y Otani, A Papp, B Pigeau, P Pirro, W Porod, F Porrati, H Qin, Bivas Rana, T Reimann, F Riente, O Romero-Isart, A Ross, A V Sadovnikov, A R Safin, E Saitoh, G Schmidt, H Schultheiss, K Schultheiss, A A Serga, S Sharma, J M Shaw, D Suess, O Surzhenko, Krzysztof Szulc, T Taniguchi, M Urbanek, K Usami, A B Ustinov, T van der Sar, S van Dijken, V I Vasyuchka, R Verba, Viola S Kusminskiy, Q Wang, M Weides, M Weiler, S Wintz, S P Wolski, X Zhang Advances in Magnetics Roadmap on Spin-Wave Computing IEEE Trans. Magn., 58 (6), pp. 1-72, 2022, ISSN: 1941-0069. @article{9706176, title = {Advances in Magnetics Roadmap on Spin-Wave Computing}, author = {A V Chumak and P Kabos and M Wu and C Abert and C Adelmann and A O Adeyeye and J Akerman and F G Aliev and A Anane and A Awad and C H Back and A Barman and G E W Bauer and M Becherer and E N Beginin and V A S V Bittencourt and Y M Blanter and P Bortolotti and I Boventer and D A Bozhko and S A Bunyaev and J J Carmiggelt and R R Cheenikundil and F Ciubotaru and S Cotofana and G Csaba and O V Dobrovolskiy and C Dubs and M Elyasi and K G Fripp and H Fulara and I A Golovchanskiy and C Gonzalez-Ballestero and Piotr Graczyk and D Grundler and Paweł Gruszecki and G Gubbiotti and K Guslienko and A Haldar and S Hamdioui and R Hertel and B Hillebrands and T Hioki and A Houshang and C -M Hu and H Huebl and M Huth and E Iacocca and M B Jungfleisch and G N Kakazei and A Khitun and R Khymyn and T Kikkawa and M Kloui and O Klein and Jarosław W. Kłos and S Knauer and S Koraltan and M Kostylev and Maciej Krawczyk and I N Krivorotov and V V Kruglyak and D Lachance-Quirion and S Ladak and R Lebrun and Y Li and M Lindner and R Macedo and S Mayr and G A Melkov and Szymon Mieszczak and Y Nakamura and H T Nembach and A A Nikitin and S A Nikitov and V Novosad and J A Otalora and Y Otani and A Papp and B Pigeau and P Pirro and W Porod and F Porrati and H Qin and Bivas Rana and T Reimann and F Riente and O Romero-Isart and A Ross and A V Sadovnikov and A R Safin and E Saitoh and G Schmidt and H Schultheiss and K Schultheiss and A A Serga and S Sharma and J M Shaw and D Suess and O Surzhenko and Krzysztof Szulc and T Taniguchi and M Urbanek and K Usami and A B Ustinov and T van der Sar and S van Dijken and V I Vasyuchka and R Verba and Viola S Kusminskiy and Q Wang and M Weides and M Weiler and S Wintz and S P Wolski and X Zhang}, doi = {10.1109/TMAG.2022.3149664}, issn = {1941-0069}, year = {2022}, date = {2022-02-07}, journal = {IEEE Trans. Magn.}, volume = {58}, number = {6}, pages = {1-72}, abstract = {Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors, which covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with the Boolean digital data, unconventional approaches, such as neuromorphic computing, and the progress toward magnon-based quantum computing. This article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors, which covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with the Boolean digital data, unconventional approaches, such as neuromorphic computing, and the progress toward magnon-based quantum computing. This article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction. |
| 32. | Krzysztof Sobucki, Paweł Gruszecki, Justyna Rychły, Maciej Krawczyk IEEE Transactions on Magnetics, 58 (2), pp. 1-5, 2022, ISSN: 1941-0069. @article{9450803, title = {Control of the Phase of Reflected Spin Waves From Magnonic Gires–Tournois Interferometer of Subwavelength Width}, author = {Krzysztof Sobucki and Paweł Gruszecki and Justyna Rychły and Maciej Krawczyk}, doi = {10.1109/TMAG.2021.3088298}, issn = {1941-0069}, year = {2022}, date = {2022-01-20}, journal = {IEEE Transactions on Magnetics}, volume = {58}, number = {2}, pages = {1-5}, abstract = {The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors. |
| 31. | Aleksandra Trzaskowska, P Graczyk, Nandan K. P. Babu, Miłosz Zdunek, H Głowiński, Jarosław W. Kłos, Sławomir Mielcarek The studies on phonons and magnons in [CoFeB/Au]N multilayers of different number of repetitions Journal of Magnetism and Magnetic Materials, 549 , pp. 169049, 2022, ISSN: 0304-8853. @article{TRZASKOWSKA2022169049, title = {The studies on phonons and magnons in [CoFeB/Au]N multilayers of different number of repetitions}, author = {Aleksandra Trzaskowska and P Graczyk and Nandan K. P. Babu and Miłosz Zdunek and H Głowiński and Jarosław W. Kłos and Sławomir Mielcarek}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322000300}, doi = {https://doi.org/10.1016/j.jmmm.2022.169049}, issn = {0304-8853}, year = {2022}, date = {2022-01-13}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {549}, pages = {169049}, abstract = {We investigated the interaction between spin waves and surface acoustic waves in the [CoFeB/Au]N multilayer deposited on the silicon substrate by Brillion light scattering spectroscopy. We showed that this kind of coupling manifested as an anticrossing in magnetoelastic dispersion relation, can be modified by changing the number of repetitions within the multilayer. The observed modification is attributed mostly to the change in the strength of dipolar interactions which alter the dispersion branch of spin wave fundamental mode and shifts the anticrossing towards larger wave vectors where the magnetoelastic coupling is stronger. The studied range of the wave vector was varied between 0.6·105 cm−1 and 2.2·105 cm−1 while the frequency range of investigations was between 3 and 20 GHz.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated the interaction between spin waves and surface acoustic waves in the [CoFeB/Au]N multilayer deposited on the silicon substrate by Brillion light scattering spectroscopy. We showed that this kind of coupling manifested as an anticrossing in magnetoelastic dispersion relation, can be modified by changing the number of repetitions within the multilayer. The observed modification is attributed mostly to the change in the strength of dipolar interactions which alter the dispersion branch of spin wave fundamental mode and shifts the anticrossing towards larger wave vectors where the magnetoelastic coupling is stronger. The studied range of the wave vector was varied between 0.6·105 cm−1 and 2.2·105 cm−1 while the frequency range of investigations was between 3 and 20 GHz. |
| 30. | Sławomir Mamica Influence of the demagnetizing field on the spin-wave softening in bicomponent magnonic crystals Journal of Magnetism and Magnetic Materials, 546 , pp. 168690, 2022, ISSN: 0304-8853. @article{MAMICA2022168690, title = {Influence of the demagnetizing field on the spin-wave softening in bicomponent magnonic crystals}, author = {Sławomir Mamica}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009264}, doi = {https://doi.org/10.1016/j.jmmm.2021.168690}, issn = {0304-8853}, year = {2022}, date = {2022-01-05}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {546}, pages = {168690}, abstract = {In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced. |
2021 |
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| 29. | Jarosław W. Kłos, Maciej Krawczyk, Szymon Mieszczak, Paweł Gruszecki 2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS), pp. 518-521, 2021. @inproceedings{9629033, title = {The interplay between spin waves and microwave magnetic field in magnetization textures and planar magnetic nanostructures}, author = {Jarosław W. Kłos and Maciej Krawczyk and Szymon Mieszczak and Paweł Gruszecki}, doi = {10.1109/COMCAS52219.2021.9629033}, year = {2021}, date = {2021-12-06}, booktitle = {2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS)}, pages = {518-521}, abstract = {The magnetic microwave field is accompanying the magnetization precession in magnetic materials. However, the precessional dynamics can propagate in the form of the dipolar spin wave only if the magnetic field can effectively mediate the coupling between the magnetic moments at the distance. We refer to counter-intuitive but well known effect - the absence of the dynamic dipolar coupling in an unconstrained and uniformly magnetized medium, to stress the role of the confined geometries and magnetization textures for shaping the dipolar interaction and molding the propagation of the dipolar spin waves. The paper discusses the electromagnetic origin of the dipolar spin waves and explains the role of magnetostatic approximation. Within this approximation, we can introduce the concept of magnetostatic potential, which is very useful for describing of the origin of the dynamic demagnetizing field providing the coupling for the dipolar spin waves.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The magnetic microwave field is accompanying the magnetization precession in magnetic materials. However, the precessional dynamics can propagate in the form of the dipolar spin wave only if the magnetic field can effectively mediate the coupling between the magnetic moments at the distance. We refer to counter-intuitive but well known effect - the absence of the dynamic dipolar coupling in an unconstrained and uniformly magnetized medium, to stress the role of the confined geometries and magnetization textures for shaping the dipolar interaction and molding the propagation of the dipolar spin waves. The paper discusses the electromagnetic origin of the dipolar spin waves and explains the role of magnetostatic approximation. Within this approximation, we can introduce the concept of magnetostatic potential, which is very useful for describing of the origin of the dynamic demagnetizing field providing the coupling for the dipolar spin waves. |
| 28. | X. Zhou, Elena V. Tartakovskaya, G. N. Kakazei, A. O. Adeyeye Phys. Rev. B, 104 , pp. 214402, 2021. @article{PhysRevB.104.214402, title = {Engineering spin wave spectra in thick Ni80Fe20 rings by using competition between exchange and dipolar fields}, author = {X. Zhou and Elena V. Tartakovskaya and G. N. Kakazei and A. O. Adeyeye}, url = {https://link.aps.org/doi/10.1103/PhysRevB.104.214402}, doi = {10.1103/PhysRevB.104.214402}, year = {2021}, date = {2021-12-03}, journal = {Phys. Rev. B}, volume = {104}, pages = {214402}, publisher = {American Physical Society}, abstract = {Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results. |
| 27. | Bivas Rana, Amrit Kumar Mondal, Supriyo Bandyopadhyay, Anjan Barman Applications of nanomagnets as dynamical systems - part II Nanotechnology, 33 (8), pp. 082002, 2021. @article{Rana_2021b, title = {Applications of nanomagnets as dynamical systems - part II}, author = {Bivas Rana and Amrit Kumar Mondal and Supriyo Bandyopadhyay and Anjan Barman}, url = {https://doi.org/10.1088/1361-6528/ac2f59}, doi = {10.1088/1361-6528/ac2f59}, year = {2021}, date = {2021-11-30}, journal = {Nanotechnology}, volume = {33}, number = {8}, pages = {082002}, publisher = {IOP Publishing}, abstract = {In Part I of this topical review, we discussed dynamical phenomena in nanomagnets, focusing primarily on magnetization reversal with an eye to digital applications. In this part, we address mostly wave-like phenomena in nanomagnets, with emphasis on spin waves in myriad nanomagnetic systems and methods of controlling magnetization dynamics in nanomagnet arrays which may have analog applications. We conclude with a discussion of some interesting spintronic phenomena that undergird the rich physics exhibited by nanomagnet assemblies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In Part I of this topical review, we discussed dynamical phenomena in nanomagnets, focusing primarily on magnetization reversal with an eye to digital applications. In this part, we address mostly wave-like phenomena in nanomagnets, with emphasis on spin waves in myriad nanomagnetic systems and methods of controlling magnetization dynamics in nanomagnet arrays which may have analog applications. We conclude with a discussion of some interesting spintronic phenomena that undergird the rich physics exhibited by nanomagnet assemblies. |
| 26. | D Kiphart, Y Harkavyi, K Balin, J Szade, Bogusław Mróz, P Kuświk, S Jurga, M Wiesner Scientific Reports, 11 (1), pp. 22980, 2021, ISSN: 2045-2322. @article{kiphart_investigations_2021, title = {Investigations of proximity-induced superconductivity in the topological insulator Bi2Te3 by microRaman spectroscopy}, author = {D Kiphart and Y Harkavyi and K Balin and J Szade and Bogusław Mróz and P Kuświk and S Jurga and M Wiesner}, url = {https://www.nature.com/articles/s41598-021-02475-w}, doi = {10.1038/s41598-021-02475-w}, issn = {2045-2322}, year = {2021}, date = {2021-11-26}, journal = {Scientific Reports}, volume = {11}, number = {1}, pages = {22980}, abstract = {We used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T textgreater Tc that converts into a superconducting state with a reduced gap for T textless Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T textgreater Tc that converts into a superconducting state with a reduced gap for T textless Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3. |
| 25. | Zbigniew Tylczyński Frontiers of Physics, 14 (6), pp. 63301, 2021, ISSN: 2095-0462. @article{tylczynski_collection_2019, title = {A collection of 505 papers on false or unconfirmed ferroelectric properties in single crystals, ceramics and polymers}, author = {Zbigniew Tylczyński}, url = {https://journal.hep.com.cn/fop/EN/10.1007/s11467-019-0912-5}, doi = {10.1007/s11467-019-0912-5}, issn = {2095-0462}, year = {2021}, date = {2021-11-19}, journal = {Frontiers of Physics}, volume = {14}, number = {6}, pages = {63301}, abstract = {textlessptextgreaterThis collection presents 505 papers on ferroelectricity in single crystals, ceramics and polymers in which pointed or elliptical hysteresis loops would testify to their ferroelectric properties. In some papers, the authors ensure that ferroelectricity can occur even in materials that do not have a polar axis of symmetry.textless/ptextgreater}, keywords = {}, pubstate = {published}, tppubtype = {article} } textlessptextgreaterThis collection presents 505 papers on ferroelectricity in single crystals, ceramics and polymers in which pointed or elliptical hysteresis loops would testify to their ferroelectric properties. In some papers, the authors ensure that ferroelectricity can occur even in materials that do not have a polar axis of symmetry.textless/ptextgreater |
| 24. | Bivas Rana, Amrit Kumar Mondal, Supriyo Bandyopadhyay, Anjan Barman Applications of nanomagnets as dynamical systems - part I Nanotechnology, 33 (6), pp. 062007, 2021. @article{Rana_2021, title = {Applications of nanomagnets as dynamical systems - part I}, author = {Bivas Rana and Amrit Kumar Mondal and Supriyo Bandyopadhyay and Anjan Barman}, url = {https://doi.org/10.1088/1361-6528/ac2e75}, doi = {10.1088/1361-6528/ac2e75}, year = {2021}, date = {2021-11-19}, journal = {Nanotechnology}, volume = {33}, number = {6}, pages = {062007}, publisher = {IOP Publishing}, abstract = {When magnets are fashioned into nanoscale elements, they exhibit a wide variety of phenomena replete with rich physics and the lure of tantalizing applications. In this topical review, we discuss some of these phenomena, especially those that have come to light recently, and highlight their potential applications. We emphasize what drives a phenomenon, what undergirds the dynamics of the system that exhibits the phenomenon, how the dynamics can be manipulated, and what specific features can be harnessed for technological advances. For the sake of balance, we point out both advantages and shortcomings of nanomagnet based devices and systems predicated on the phenomena we discuss. Where possible, we chart out paths for future investigations that can shed new light on an intriguing phenomenon and/or facilitate both traditional and non-traditional applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When magnets are fashioned into nanoscale elements, they exhibit a wide variety of phenomena replete with rich physics and the lure of tantalizing applications. In this topical review, we discuss some of these phenomena, especially those that have come to light recently, and highlight their potential applications. We emphasize what drives a phenomenon, what undergirds the dynamics of the system that exhibits the phenomenon, how the dynamics can be manipulated, and what specific features can be harnessed for technological advances. For the sake of balance, we point out both advantages and shortcomings of nanomagnet based devices and systems predicated on the phenomena we discuss. Where possible, we chart out paths for future investigations that can shed new light on an intriguing phenomenon and/or facilitate both traditional and non-traditional applications. |
| 23. | Marek Vanatka, Krzysztof Szulc, Ondrej Wojewoda, Carsten Dubs, Andrii V Chumak, Maciej Krawczyk, Oleksandr V Dobrovolskiy, Jarosław W. Kłos, Michal Urbánek Spin-Wave Dispersion Measurement by Variable-Gap Propagating Spin-Wave Spectroscopy Phys. Rev. Applied, 16 , pp. 054033, 2021. @article{PhysRevApplied.16.054033, title = {Spin-Wave Dispersion Measurement by Variable-Gap Propagating Spin-Wave Spectroscopy}, author = {Marek Vanatka and Krzysztof Szulc and Ondrej Wojewoda and Carsten Dubs and Andrii V Chumak and Maciej Krawczyk and Oleksandr V Dobrovolskiy and Jarosław W. Kłos and Michal Urbánek}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.16.054033}, doi = {10.1103/PhysRevApplied.16.054033}, year = {2021}, date = {2021-11-17}, journal = {Phys. Rev. Applied}, volume = {16}, pages = {054033}, publisher = {American Physical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |