Publications by Department of Physics of Nanostructures
Departments of ISQI | Publications of ISQI
2021 |
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| 22. | Michal Mruczkiewicz, Paweł Gruszecki The 2021 roadmap for noncollinear magnonics Solid State Physics, 2021, ISSN: 0081-1947. @article{MRUCZKIEWICZ2021, title = {The 2021 roadmap for noncollinear magnonics}, author = {Michal Mruczkiewicz and Paweł Gruszecki}, url = {https://www.sciencedirect.com/science/article/pii/S0081194721000059}, doi = {https://doi.org/10.1016/bs.ssp.2021.09.001}, issn = {0081-1947}, year = {2021}, date = {2021-10-23}, journal = {Solid State Physics}, publisher = {Academic Press}, series = {Solid State Physics}, abstract = {Noncollinear magnonics is a rapidly developing topic of modern magnetism focusing on spin wave (magnon) dynamics in noncollinear spin textures. One of the driving forces of this research field is to employ nanosize dynamical noncollinear spin textures for the control and guiding of magnons. An unquestionable advantage of this approach is the potential to design programmable nanochannels with sizes below patterning limits. Furthermore, the noncollinear magnetic states induce nontrivial dynamical effects suitable for tailoring of SW propagation properties and emission of SWs. In the following, we will summarize the recent achievements of the field and discuss of current and future challenges.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Noncollinear magnonics is a rapidly developing topic of modern magnetism focusing on spin wave (magnon) dynamics in noncollinear spin textures. One of the driving forces of this research field is to employ nanosize dynamical noncollinear spin textures for the control and guiding of magnons. An unquestionable advantage of this approach is the potential to design programmable nanochannels with sizes below patterning limits. Furthermore, the noncollinear magnetic states induce nontrivial dynamical effects suitable for tailoring of SW propagation properties and emission of SWs. In the following, we will summarize the recent achievements of the field and discuss of current and future challenges. |
| 21. | Mateusz Zelent, Iuliia V Vetrova, Jan Šoltýs, Xiaoguang Li, Yan Zhou, Vladislav A Gubanov, Alexandr V Sadovnikov, Tomas Šcepka, Jan Dérer, Roman Stoklas, Vladimír Cambel, Michal Mruczkiewicz Skyrmion Formation in Nanodisks Using Magnetic Force Microscopy Tip Nanomaterials, 11 (10), 2021, ISSN: 2079-4991. @article{nano11102627, title = {Skyrmion Formation in Nanodisks Using Magnetic Force Microscopy Tip}, author = {Mateusz Zelent and Iuliia V Vetrova and Jan Šoltýs and Xiaoguang Li and Yan Zhou and Vladislav A Gubanov and Alexandr V Sadovnikov and Tomas Šcepka and Jan Dérer and Roman Stoklas and Vladimír Cambel and Michal Mruczkiewicz}, url = {https://www.mdpi.com/2079-4991/11/10/2627}, doi = {10.3390/nano11102627}, issn = {2079-4991}, year = {2021}, date = {2021-10-06}, journal = {Nanomaterials}, volume = {11}, number = {10}, abstract = {We demonstrated numerically the skyrmion formation in ultrathin nanodisks using a magnetic force microscopy tip. We found that the local magnetic field generated by the magnetic tip significantly affects the magnetization state of the nanodisks and leads to the formation of skyrmions. Experimentally, we confirmed the influence of the local field on the magnetization states of the disks. Micromagnetic simulations explain the evolution of the magnetic state during magnetic force microscopy scanning and confirm the possibility of skyrmion formation. The formation of the horseshoe magnetic domain is a key transition from random labyrinth domain states into the skyrmion state. We showed that the formation of skyrmions by the magnetic probe is a reliable and repetitive procedure. Our findings provide a simple solution for skyrmion formation in nanodisks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We demonstrated numerically the skyrmion formation in ultrathin nanodisks using a magnetic force microscopy tip. We found that the local magnetic field generated by the magnetic tip significantly affects the magnetization state of the nanodisks and leads to the formation of skyrmions. Experimentally, we confirmed the influence of the local field on the magnetization states of the disks. Micromagnetic simulations explain the evolution of the magnetic state during magnetic force microscopy scanning and confirm the possibility of skyrmion formation. The formation of the horseshoe magnetic domain is a key transition from random labyrinth domain states into the skyrmion state. We showed that the formation of skyrmions by the magnetic probe is a reliable and repetitive procedure. Our findings provide a simple solution for skyrmion formation in nanodisks. |
| 20. | Anjan Barman, Gianluca Gubbiotti, S Ladak, A O Adeyeye, Maciej Krawczyk, J Gräfe, C Adelmann, S Cotofana, A Naeemi, V I Vasyuchka, B Hillebrands, S A Nikitov, H Yu, D Grundler, A V Sadovnikov, A A Grachev, S E Sheshukova, J-Y Duquesne, M Marangolo, G Csaba, W Porod, V E Demidov, S Urazhdin, S O Demokritov, E Albisetti, D Petti, R Bertacco, H Schultheiss, V V Kruglyak, V D Poimanov, S Sahoo, J Sinha, H Yang, M Münzenberg, T Moriyama, S Mizukami, P Landeros, R A Gallardo, G Carlotti, J-V Kim, R L Stamps, R E Camley, Bivas Rana, Y Otani, W Yu, T Yu, G E W Bauer, C Back, G S Uhrig, O V Dobrovolskiy, B Budinska, H Qin, S van Dijken, A V Chumak, A Khitun, D E Nikonov, I A Young, B W Zingsem, M Winklhofer Journal of Physics: Condensed Matter, 33 (41), pp. 413001, 2021. @article{Barman_2021, title = {The 2021 Magnonics Roadmap}, author = {Anjan Barman and Gianluca Gubbiotti and S Ladak and A O Adeyeye and Maciej Krawczyk and J Gräfe and C Adelmann and S Cotofana and A Naeemi and V I Vasyuchka and B Hillebrands and S A Nikitov and H Yu and D Grundler and A V Sadovnikov and A A Grachev and S E Sheshukova and J-Y Duquesne and M Marangolo and G Csaba and W Porod and V E Demidov and S Urazhdin and S O Demokritov and E Albisetti and D Petti and R Bertacco and H Schultheiss and V V Kruglyak and V D Poimanov and S Sahoo and J Sinha and H Yang and M Münzenberg and T Moriyama and S Mizukami and P Landeros and R A Gallardo and G Carlotti and J-V Kim and R L Stamps and R E Camley and Bivas Rana and Y Otani and W Yu and T Yu and G E W Bauer and C Back and G S Uhrig and O V Dobrovolskiy and B Budinska and H Qin and S van Dijken and A V Chumak and A Khitun and D E Nikonov and I A Young and B W Zingsem and M Winklhofer}, url = {https://doi.org/10.1088/1361-648x/abec1a}, doi = {10.1088/1361-648x/abec1a}, year = {2021}, date = {2021-08-18}, journal = {Journal of Physics: Condensed Matter}, volume = {33}, number = {41}, pages = {413001}, publisher = {IOP Publishing}, abstract = {Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research papers, review articles, citations, proposals of devices as well as introduction of new sub-topics prompted us to present the first roadmap on magnonics. This is a collection of 22 sections written by leading experts in this field who review and discuss the current status besides presenting their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and its interconnections to standard electronics. To this end, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This roadmap asserts a milestone for future emerging research directions in magnonics, and hopefully, it will inspire a series of exciting new articles on the same topic in the coming years.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research papers, review articles, citations, proposals of devices as well as introduction of new sub-topics prompted us to present the first roadmap on magnonics. This is a collection of 22 sections written by leading experts in this field who review and discuss the current status besides presenting their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and its interconnections to standard electronics. To this end, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This roadmap asserts a milestone for future emerging research directions in magnonics, and hopefully, it will inspire a series of exciting new articles on the same topic in the coming years. |
| 19. | Veysel Erçağlar, Hodjat Hajian, Andriy E. Serebryannikov, Ekmel Ozbay Multifunctional tunable gradient metasurfaces for terahertz beam splitting and light absorption Opt. Lett., 46 (16), pp. 3953–3956, 2021. @article{Ercaglar:21, title = {Multifunctional tunable gradient metasurfaces for terahertz beam splitting and light absorption}, author = {Veysel Erçağlar and Hodjat Hajian and Andriy E. Serebryannikov and Ekmel Ozbay}, url = {http://ol.osa.org/abstract.cfm?URI=ol-46-16-3953}, doi = {10.1364/OL.435197}, year = {2021}, date = {2021-08-09}, journal = {Opt. Lett.}, volume = {46}, number = {16}, pages = {3953--3956}, publisher = {OSA}, abstract = {Obtaining functional devices with tunable features is beneficial to advance terahertz (THz) science and technology. Here, we propose multifunctional gradient metasurfaces that are composed of a periodic array of binary Si microcylinders integrated with VO2 and graphene. The metasurfaces act as transmittive (reflective) beamsplitters for the dielectric (metallic) phase of VO2 with a switchable characteristic. Moreover, by integrating the metasurfaces with graphene and modifying its chemical potential, one can tune the intensity of the split beam as well as obtain nearly perfect resonant absorptions. Consequently, the proposed metasurfaces can find potential applications in THz interferometers, multiplexers, and light absorbers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Obtaining functional devices with tunable features is beneficial to advance terahertz (THz) science and technology. Here, we propose multifunctional gradient metasurfaces that are composed of a periodic array of binary Si microcylinders integrated with VO2 and graphene. The metasurfaces act as transmittive (reflective) beamsplitters for the dielectric (metallic) phase of VO2 with a switchable characteristic. Moreover, by integrating the metasurfaces with graphene and modifying its chemical potential, one can tune the intensity of the split beam as well as obtain nearly perfect resonant absorptions. Consequently, the proposed metasurfaces can find potential applications in THz interferometers, multiplexers, and light absorbers. |
| 18. | Piotr Graczyk, Maciej Krawczyk Scientific Reports, 11 (1), pp. 15692, 2021. @article{graczyk_nonresonant_2021, title = {Nonresonant amplification of spin waves through interface magnetoelectric effect and spin-transfer torque}, author = {Piotr Graczyk and Maciej Krawczyk}, url = {https://www.nature.com/articles/s41598-021-95267-1}, doi = {10.1038/s41598-021-95267-1}, year = {2021}, date = {2021-08-03}, urldate = {2021-08-03}, journal = {Scientific Reports}, volume = {11}, number = {1}, pages = {15692}, abstract = {We present a new mechanism for manipulation of the spin-wave amplitude through the use of the dynamic charge-mediated magnetoelectric effect in ultrathin multilayers composed of dielectric thin-film capacitors separated by a ferromagnetic bilayer. Propagating spin waves can be amplified and attenuated with rising and decreasing slopes of the oscillating voltage, respectively, locally applied to the sample. The way the spin accumulation is generated makes the interaction of the spin-transfer torque with the magnetization dynamics mode-selective and restricted to some range of spin-wave frequencies, which is contrary to known types of the spin-transfer torque effects. The interfacial nature of spin-dependent screening allows to reduce the thickness of the fixed magnetization layer to a few nanometers, thus the proposed effect significantly contributes toward realization of the magnonic devices and also miniaturization of the spintronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a new mechanism for manipulation of the spin-wave amplitude through the use of the dynamic charge-mediated magnetoelectric effect in ultrathin multilayers composed of dielectric thin-film capacitors separated by a ferromagnetic bilayer. Propagating spin waves can be amplified and attenuated with rising and decreasing slopes of the oscillating voltage, respectively, locally applied to the sample. The way the spin accumulation is generated makes the interaction of the spin-transfer torque with the magnetization dynamics mode-selective and restricted to some range of spin-wave frequencies, which is contrary to known types of the spin-transfer torque effects. The interfacial nature of spin-dependent screening allows to reduce the thickness of the fixed magnetization layer to a few nanometers, thus the proposed effect significantly contributes toward realization of the magnonic devices and also miniaturization of the spintronic devices. |
| 17. | Aleksandra Trzaskowska, Sławomir Mielcarek, M Wiesner, F Lombardi, Bogusław Mróz Ultrasonics, 117 , pp. 106526, 2021. @article{TRZASKOWSKA2021106526, title = {Dispersion of the surface phonons in semiconductor/topological insulator Si/Bi2Te3 heterostructure studied by high resolution Brillouin spectroscopy}, author = {Aleksandra Trzaskowska and Sławomir Mielcarek and M Wiesner and F Lombardi and Bogusław Mróz}, url = {https://www.sciencedirect.com/science/article/pii/S0041624X21001554}, doi = {https://doi.org/10.1016/j.ultras.2021.106526}, year = {2021}, date = {2021-07-21}, journal = {Ultrasonics}, volume = {117}, pages = {106526}, abstract = {The dynamics and dispersion of surface phonons in heterostructure semiconductor/ topological insulator Si/Bi2Te3 was investigated using high resolution Brillouin light scattering method in the GHz frequency range. Both Rayleigh and Sezawa surface acoustic waves have been observed for wave vectors ranging from 0.006 to 0.023 nm−1. Anomaly in dispersion relations ω(q) for both surface waves were detected for the wave vector q = 0.016 nm−1. The finite element method (FEM) was used to simulate the observed shapes of ω(q) and to find the deformation profiles of surface acoustic waves. We attribute the observed changes to the coupling between low energy electrons and surface phonons. The coupling between helical Dirac states and surface phonons is discussed in the frame of accessible theoretical models.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The dynamics and dispersion of surface phonons in heterostructure semiconductor/ topological insulator Si/Bi2Te3 was investigated using high resolution Brillouin light scattering method in the GHz frequency range. Both Rayleigh and Sezawa surface acoustic waves have been observed for wave vectors ranging from 0.006 to 0.023 nm−1. Anomaly in dispersion relations ω(q) for both surface waves were detected for the wave vector q = 0.016 nm−1. The finite element method (FEM) was used to simulate the observed shapes of ω(q) and to find the deformation profiles of surface acoustic waves. We attribute the observed changes to the coupling between low energy electrons and surface phonons. The coupling between helical Dirac states and surface phonons is discussed in the frame of accessible theoretical models. |
| 16. | Pontus Laurell, Allen Scheie, Chiron J Mukherjee, Michael M Koza, Mechtild Enderle, Zbigniew Tylczyński, Satoshi Okamoto, Radu Coldea, Alan D Tennant, Gonzalo Alvarez Quantifying and Controlling Entanglement in the Quantum Magnet Cs2CoCl4 Phys. Rev. Lett., 127 , pp. 037201, 2021. @article{PhysRevLett.127.037201, title = {Quantifying and Controlling Entanglement in the Quantum Magnet Cs2CoCl4}, author = {Pontus Laurell and Allen Scheie and Chiron J Mukherjee and Michael M Koza and Mechtild Enderle and Zbigniew Tylczyński and Satoshi Okamoto and Radu Coldea and Alan D Tennant and Gonzalo Alvarez}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.127.037201}, doi = {10.1103/PhysRevLett.127.037201}, year = {2021}, date = {2021-07-13}, journal = {Phys. Rev. Lett.}, volume = {127}, pages = {037201}, publisher = {American Physical Society}, abstract = {The lack of methods to experimentally detect and quantify entanglement in quantum matter impedes our ability to identify materials hosting highly entangled phases, such as quantum spin liquids. We thus investigate the feasibility of using inelastic neutron scattering (INS) to implement a model-independent measurement protocol for entanglement based on three entanglement witnesses: one-tangle, two-tangle, and quantum Fisher information (QFI). We perform high-resolution INS measurements on Cs2CoCl4, a close realization of the S=1/2 transverse-field XXZ spin chain, where we can control entanglement using the magnetic field, and compare with density-matrix renormalization group calculations for validation. The three witnesses allow us to infer entanglement properties and make deductions about the quantum state in the material. We find QFI to be a particularly robust experimental probe of entanglement, whereas the one and two-tangles require more careful analysis. Our results lay the foundation for a general entanglement detection protocol for quantum spin systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lack of methods to experimentally detect and quantify entanglement in quantum matter impedes our ability to identify materials hosting highly entangled phases, such as quantum spin liquids. We thus investigate the feasibility of using inelastic neutron scattering (INS) to implement a model-independent measurement protocol for entanglement based on three entanglement witnesses: one-tangle, two-tangle, and quantum Fisher information (QFI). We perform high-resolution INS measurements on Cs2CoCl4, a close realization of the S=1/2 transverse-field XXZ spin chain, where we can control entanglement using the magnetic field, and compare with density-matrix renormalization group calculations for validation. The three witnesses allow us to infer entanglement properties and make deductions about the quantum state in the material. We find QFI to be a particularly robust experimental probe of entanglement, whereas the one and two-tangles require more careful analysis. Our results lay the foundation for a general entanglement detection protocol for quantum spin systems. |
| 15. | T F Gundogdu, M Gokkavas, Andriy E. Serebryannikov, E Ozbay Evidence of asymmetric beaming in a piecewise-linear propagation channel Opt. Lett., 46 (12), pp. 2928–2931, 2021. @article{Gundogdu:21, title = {Evidence of asymmetric beaming in a piecewise-linear propagation channel}, author = {T F Gundogdu and M Gokkavas and Andriy E. Serebryannikov and E Ozbay}, url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-46-12-2928}, doi = {10.1364/OL.420297}, year = {2021}, date = {2021-06-14}, journal = {Opt. Lett.}, volume = {46}, number = {12}, pages = {2928--2931}, publisher = {Optica Publishing Group}, abstract = {Asymmetric beaming in a piecewise-linear propagation channel is demonstrated for a single photonic-crystal prism at Gaussian-beam illumination. The used hybrid refraction--diffraction mechanism exploits oblique incidence, the first-negative-order deflection at the longer interface, and asymmetry in coupling at the exit interfaces and does not need blocking of transmission by dispersion in the backward illumination case. The Floquet--Bloch mode with left-handed behavior and nearly circular equifrequency dispersion contours is utilized. The outgoing waves may have significantly different spatial distributions for the forward and backward illumination cases, yielding asymmetry in the beaming regime.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Asymmetric beaming in a piecewise-linear propagation channel is demonstrated for a single photonic-crystal prism at Gaussian-beam illumination. The used hybrid refraction--diffraction mechanism exploits oblique incidence, the first-negative-order deflection at the longer interface, and asymmetry in coupling at the exit interfaces and does not need blocking of transmission by dispersion in the backward illumination case. The Floquet--Bloch mode with left-handed behavior and nearly circular equifrequency dispersion contours is utilized. The outgoing waves may have significantly different spatial distributions for the forward and backward illumination cases, yielding asymmetry in the beaming regime. |
| 14. | Felix Groß, Mateusz Zelent, Ajay Gangwar, Sławomir Mamica, Paweł Gruszecki, Matthias Werner, Gisela Schütz, Markus Weigand, Eberhard J Goering, Christian H Back, Maciej Krawczyk, Joachim Gräfe Phase resolved observation of spin wave modes in antidot lattices Appl. Phys. Lett., 118 (23), pp. 232403, 2021. @article{doi:10.1063/5.0045142, title = {Phase resolved observation of spin wave modes in antidot lattices}, author = {Felix Groß and Mateusz Zelent and Ajay Gangwar and Sławomir Mamica and Paweł Gruszecki and Matthias Werner and Gisela Schütz and Markus Weigand and Eberhard J Goering and Christian H Back and Maciej Krawczyk and Joachim Gräfe}, url = {https://doi.org/10.1063/5.0045142}, doi = {10.1063/5.0045142}, year = {2021}, date = {2021-06-10}, journal = {Appl. Phys. Lett.}, volume = {118}, number = {23}, pages = {232403}, abstract = {Antidot lattices have proven to be a powerful tool for spin wave band structure manipulation. Utilizing time-resolved scanning transmission x-ray microscopy, we are able to experimentally image edge-localized spin wave modes in an antidot lattice with a lateral confinement down to <80nm x 130 nm. At higher frequencies, spin wave dragonfly patterns formed by the demagnetizing structures of the antidot lattice are excited. Evaluating their relative phase with respect to the propagating mode within the antidot channel reveals that the dragonfly modes are not directly excited by the antenna but need the propagating mode as an energy mediator. Furthermore, micromagnetic simulations reveal that additional dispersion branches exist for a tilted external field geometry. These branches correspond to asymmetric spin wave modes that cannot be excited in a non-tilted field geometry due to the symmetry restriction. In addition to the band having a negative slope, these asymmetric modes also cause an unexpected transformation of the band structure, slightly reaching into the otherwise empty bandgap between the low frequency edge modes and the fundamental mode. The presented phase resolved investigation of spin waves is a crucial step for spin wave manipulation in magnonic crystals.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Antidot lattices have proven to be a powerful tool for spin wave band structure manipulation. Utilizing time-resolved scanning transmission x-ray microscopy, we are able to experimentally image edge-localized spin wave modes in an antidot lattice with a lateral confinement down to <80nm x 130 nm. At higher frequencies, spin wave dragonfly patterns formed by the demagnetizing structures of the antidot lattice are excited. Evaluating their relative phase with respect to the propagating mode within the antidot channel reveals that the dragonfly modes are not directly excited by the antenna but need the propagating mode as an energy mediator. Furthermore, micromagnetic simulations reveal that additional dispersion branches exist for a tilted external field geometry. These branches correspond to asymmetric spin wave modes that cannot be excited in a non-tilted field geometry due to the symmetry restriction. In addition to the band having a negative slope, these asymmetric modes also cause an unexpected transformation of the band structure, slightly reaching into the otherwise empty bandgap between the low frequency edge modes and the fundamental mode. The presented phase resolved investigation of spin waves is a crucial step for spin wave manipulation in magnonic crystals. |
| 13. | Iu. V Vetrova, Mateusz Zelent, J Šoltýs, V A Gubanov, A V Sadovnikov, T Šcepka, J Dérer, R Stoklas, V Cambel, M Mruczkiewicz Investigation of self-nucleated skyrmion states in the ferromagnetic/nonmagnetic multilayer dot Appl. Phys. Lett., 118 (21), pp. 212409, 2021. @article{doi:10.1063/5.0045835, title = {Investigation of self-nucleated skyrmion states in the ferromagnetic/nonmagnetic multilayer dot}, author = {Iu. V Vetrova and Mateusz Zelent and J Šoltýs and V A Gubanov and A V Sadovnikov and T Šcepka and J Dérer and R Stoklas and V Cambel and M Mruczkiewicz}, doi = {10.1063/5.0045835}, year = {2021}, date = {2021-05-28}, journal = {Appl. Phys. Lett.}, volume = {118}, number = {21}, pages = {212409}, abstract = {Understanding the stability of magnetic textures in multilayer patterned dots would constitute a significant step toward skyrmion-based applications. Here, we report the observation of skyrmions in patterned nanodots composed of multilayers. We examine the stabilization of various magnetic states such as single-domain states, skyrmion states, horseshoe-like domain structures, and worm-like domain structures in submicrometer dots (diameters 150–525 nm). Dots are fabricated from Pt/Co/Au multilayer structures that exhibit the interfacial Dzyaloshinskii–Moriya interaction and perpendicular magnetic anisotropy. In particular, we show that a stack of six repetitions of Pt/Co/Au layers suffices to stabilize the skyrmion state inside a dot at room temperature. A micromagnetic simulation determines the regime of skyrmion stability. The results reveal a correlation between the magnetic-force microscopy measurements and the micromagnetic simulation. Furthermore, we explain the development of the magnetic state with increasing dot diameter. We envision that nanopatterning of multilayer magnetic films could serve as a versatile way of creating magnetic skyrmion states.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Understanding the stability of magnetic textures in multilayer patterned dots would constitute a significant step toward skyrmion-based applications. Here, we report the observation of skyrmions in patterned nanodots composed of multilayers. We examine the stabilization of various magnetic states such as single-domain states, skyrmion states, horseshoe-like domain structures, and worm-like domain structures in submicrometer dots (diameters 150–525 nm). Dots are fabricated from Pt/Co/Au multilayer structures that exhibit the interfacial Dzyaloshinskii–Moriya interaction and perpendicular magnetic anisotropy. In particular, we show that a stack of six repetitions of Pt/Co/Au layers suffices to stabilize the skyrmion state inside a dot at room temperature. A micromagnetic simulation determines the regime of skyrmion stability. The results reveal a correlation between the magnetic-force microscopy measurements and the micromagnetic simulation. Furthermore, we explain the development of the magnetic state with increasing dot diameter. We envision that nanopatterning of multilayer magnetic films could serve as a versatile way of creating magnetic skyrmion states. |
| 12. | Tomasz Lehmann, Magdalena Wojtków, Ewa Pruszynska-Oszmałek, Paweł Kołodziejski, Celina Pezowicz, Aleksandra Trzaskowska, Sławomir Mielcarek, Mirosław Szybowicz, Ariadna B Nowicka, Marek Nowicki, Ewa Misterska, Ewa Iwańczyk-Skalska, Paweł Jagodziński, Maciej Głowacki Acta of Bioengineering and Biomechanics, 23 (3), pp. 1 -17, 2021. @article{000231402, title = {Trabecular bone remodelling in the femur of C57BL/6J mice treated with diclofenac in combination with treadmill exercise}, author = {Tomasz Lehmann and Magdalena Wojtków and Ewa Pruszynska-Oszmałek and Paweł Kołodziejski and Celina Pezowicz and Aleksandra Trzaskowska and Sławomir Mielcarek and Mirosław Szybowicz and Ariadna B Nowicka and Marek Nowicki and Ewa Misterska and Ewa Iwańczyk-Skalska and Paweł Jagodziński and Maciej Głowacki}, url = {http://www.actabio.pwr.wroc.pl/Vol23No3/41.pdf}, year = {2021}, date = {2021-05-13}, journal = {Acta of Bioengineering and Biomechanics}, volume = {23}, number = {3}, pages = {1 -17}, abstract = {Analgesic treatment with diclofenac deteriorates bone structure and decreases biomechanical properties. This bone loss has been though to be reversed by training. The impact of exercise on bone treated with diclofenac (DF) has reminded elusive. In the present study, we assayed the combined impact of exercises and DF on mouse femur. Methods: The femur samples we obtained from 30 days treated C57BL/6J female mice. The training group ran on a horizontal treadmill at 12 m/min by 30 min a day (5% grade/slope). The group of ten mice treated with DF received the drug subcutaneously every day (5 mg/kg of body weight/day). The combined group ran on the treadmill and obtained DF. After 30 days, we sacrificed mice and studied their femurs using microcomputed tomography (μCT), dynamic mechanical analysis (DMA) and nanoindentation. Results: We observed that treadmill running and DF decreased trabecular bone volume and mineral density. Combined effect of training and DF was not additive. A significant interaction of both parameters suggested protective effect of training on bone loss provoked by DF. The femur cortical bone shell remained untouched by the training and treatment. The training and the DF treatment did not alter the storage modulus E significantly. The unchanged storage modulus would be suggesting on the unaltered bone strength. Conclusions: We concluded that even relatively short time of training with concomitant DF treatment could be protective on trabecular bone. Although viscoelastic properties of the entire femur were not modulated, femur trabecular tissue was thinned by treatment with DF and protected by training.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Analgesic treatment with diclofenac deteriorates bone structure and decreases biomechanical properties. This bone loss has been though to be reversed by training. The impact of exercise on bone treated with diclofenac (DF) has reminded elusive. In the present study, we assayed the combined impact of exercises and DF on mouse femur. Methods: The femur samples we obtained from 30 days treated C57BL/6J female mice. The training group ran on a horizontal treadmill at 12 m/min by 30 min a day (5% grade/slope). The group of ten mice treated with DF received the drug subcutaneously every day (5 mg/kg of body weight/day). The combined group ran on the treadmill and obtained DF. After 30 days, we sacrificed mice and studied their femurs using microcomputed tomography (μCT), dynamic mechanical analysis (DMA) and nanoindentation. Results: We observed that treadmill running and DF decreased trabecular bone volume and mineral density. Combined effect of training and DF was not additive. A significant interaction of both parameters suggested protective effect of training on bone loss provoked by DF. The femur cortical bone shell remained untouched by the training and treatment. The training and the DF treatment did not alter the storage modulus E significantly. The unchanged storage modulus would be suggesting on the unaltered bone strength. Conclusions: We concluded that even relatively short time of training with concomitant DF treatment could be protective on trabecular bone. Although viscoelastic properties of the entire femur were not modulated, femur trabecular tissue was thinned by treatment with DF and protected by training. |
| 11. | Pierre Roberjot, Krzysztof Szulc, Jarosław W. Kłos, Maciej Krawczyk Appl. Phys. Lett., 118 (18), pp. 182406, 2021. @article{doi:10.1063/5.0046001b, title = {Multifunctional operation of the double-layer ferromagnetic structure coupled by a rectangular nanoresonator}, author = {Pierre Roberjot and Krzysztof Szulc and Jarosław W. Kłos and Maciej Krawczyk}, url = {https://doi.org/10.1063/5.0046001}, doi = {10.1063/5.0046001}, year = {2021}, date = {2021-05-05}, journal = {Appl. Phys. Lett.}, volume = {118}, number = {18}, pages = {182406}, abstract = {The use of spin waves as a signal carrier requires developing the functional elements allowing for multiplexing and demultiplexing information coded at different wavelengths. For this purpose, we propose a system of thin ferromagnetic layers dynamically coupled by a rectangular ferromagnetic resonator. We show that single and double, clockwise and counterclockwise, circulating modes of the resonator offer a wide possibility of control of propagating waves. Particularly, at frequency related to the double-clockwise circulating spin-wave mode of the resonator, the spin wave excited in one layer is transferred to the second one where it propagates in the backward direction. Interestingly, the wave excited in the second layer propagates in the forward direction only in that layer. This demonstrates add-drop filtering and circulator functionality. Thus, the proposed system can become an important part of future magnonic technology for signal routing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The use of spin waves as a signal carrier requires developing the functional elements allowing for multiplexing and demultiplexing information coded at different wavelengths. For this purpose, we propose a system of thin ferromagnetic layers dynamically coupled by a rectangular ferromagnetic resonator. We show that single and double, clockwise and counterclockwise, circulating modes of the resonator offer a wide possibility of control of propagating waves. Particularly, at frequency related to the double-clockwise circulating spin-wave mode of the resonator, the spin wave excited in one layer is transferred to the second one where it propagates in the backward direction. Interestingly, the wave excited in the second layer propagates in the forward direction only in that layer. This demonstrates add-drop filtering and circulator functionality. Thus, the proposed system can become an important part of future magnonic technology for signal routing. |
| 10. | Ataollah Kalantari Osgouei, Hodjat Hajian, Andriy E. Serebryannikov, Ekmel Ozbay J. Phys. D: Appl. Phys., 54 (27), pp. 275102, 2021. @article{Osgouei_2021, title = {Hybrid indium tin oxide-Au metamaterial as a multiband bi-functional light absorber in the visible and near-infrared ranges}, author = {Ataollah Kalantari Osgouei and Hodjat Hajian and Andriy E. Serebryannikov and Ekmel Ozbay}, url = {https://doi.org/10.1088/1361-6463/abf579}, doi = {10.1088/1361-6463/abf579}, year = {2021}, date = {2021-04-23}, journal = {J. Phys. D: Appl. Phys.}, volume = {54}, number = {27}, pages = {275102}, publisher = {IOP Publishing}, abstract = {Metamaterial nearly perfect light absorbers (MPAs) with dual-narrowband functionality—that absorb light in two narrowband adjacent wavelength regions—have attracted considerable attention due to their intriguing applications, such as sensing, photovoltaic, and thermal emission. Here, we propose a multi-band MPA with two narrowband absorption responses that are centered on the visible and near-infrared (NIR) wavelengths (773 nm and 900 nm, respectively) and a broadband absorptive characteristic in another window in the NIR region (ranging from 1530 nm to 2700 nm with a bandwidth of 1170 nm). The MPA comprises a periodic array of self-aligned hybrid indium tin oxide (ITO)-Au split-ring-resonators that are separated from an optically thick bottom reflector with a SiO2 layer. Based on numerical calculations, which are accompanied with a semi-analytical examination, we find that the dual narrowband and broadband responses are attributed to the hybridization of the optical responses of gold as a plasmonic material with the ones of ITO. Note that ITO acts as a low-loss dielectric in the visible range and a lossy plasmonic material in the NIR region. Moreover, due to the applied symmetry in the unit cell of the metamaterial, the proposed MPA represents polarization insensitive and omnidirectional absorptive features. The proposed metastructure can find potential applications in selective thermophotovoltaic devices, thermal emitters, and sensors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metamaterial nearly perfect light absorbers (MPAs) with dual-narrowband functionality—that absorb light in two narrowband adjacent wavelength regions—have attracted considerable attention due to their intriguing applications, such as sensing, photovoltaic, and thermal emission. Here, we propose a multi-band MPA with two narrowband absorption responses that are centered on the visible and near-infrared (NIR) wavelengths (773 nm and 900 nm, respectively) and a broadband absorptive characteristic in another window in the NIR region (ranging from 1530 nm to 2700 nm with a bandwidth of 1170 nm). The MPA comprises a periodic array of self-aligned hybrid indium tin oxide (ITO)-Au split-ring-resonators that are separated from an optically thick bottom reflector with a SiO2 layer. Based on numerical calculations, which are accompanied with a semi-analytical examination, we find that the dual narrowband and broadband responses are attributed to the hybridization of the optical responses of gold as a plasmonic material with the ones of ITO. Note that ITO acts as a low-loss dielectric in the visible range and a lossy plasmonic material in the NIR region. Moreover, due to the applied symmetry in the unit cell of the metamaterial, the proposed MPA represents polarization insensitive and omnidirectional absorptive features. The proposed metastructure can find potential applications in selective thermophotovoltaic devices, thermal emitters, and sensors. |
| 9. | Krzysztof Szulc, Simon Mendisch, Michał Mruczkiewicz, Francesca Casoli, Markus Becherer, Gianluca Gubbiotti Nonreciprocal spin-wave dynamics in Pt/Co/W/Co/Pt multilayers Phys. Rev. B, 103 , pp. 134404, 2021. @article{PhysRevB.103.134404, title = {Nonreciprocal spin-wave dynamics in Pt/Co/W/Co/Pt multilayers}, author = {Krzysztof Szulc and Simon Mendisch and Michał Mruczkiewicz and Francesca Casoli and Markus Becherer and Gianluca Gubbiotti}, url = {https://link.aps.org/doi/10.1103/PhysRevB.103.134404}, doi = {10.1103/PhysRevB.103.134404}, year = {2021}, date = {2021-04-01}, journal = {Phys. Rev. B}, volume = {103}, pages = {134404}, publisher = {American Physical Society}, abstract = {We present a detailed study of the spin-wave dynamics in single Pt/Co/W and double Pt/Co/W/Co/Pt ferromagnetic layer systems. The dispersion of spin waves was measured by wave-vector-resolved Brillouin light scattering spectroscopy while the in-plane and out-of-plane magnetization curves were measured by alternating gradient field magnetometry. The interfacial Dzyaloshinskii-Moriya interaction induced nonreciprocal dispersion relation was demonstrated for both single and double ferromagnetic layers and explicated by numerical simulations and theoretical formulas. The results indicate the crucial role of the order of layers deposition on the magnetic parameters. A significant difference between the perpendicular magnetic anisotropy constant in double ferromagnetic layer systems conduces to the decline of the interlayer interactions and different dispersion relations for the spin-wave modes. Our study provides a significant contribution to the realization of the multifunctional nonreciprocal magnonic devices based on ultrathin ferromagnetic/heavy-metal layer systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a detailed study of the spin-wave dynamics in single Pt/Co/W and double Pt/Co/W/Co/Pt ferromagnetic layer systems. The dispersion of spin waves was measured by wave-vector-resolved Brillouin light scattering spectroscopy while the in-plane and out-of-plane magnetization curves were measured by alternating gradient field magnetometry. The interfacial Dzyaloshinskii-Moriya interaction induced nonreciprocal dispersion relation was demonstrated for both single and double ferromagnetic layers and explicated by numerical simulations and theoretical formulas. The results indicate the crucial role of the order of layers deposition on the magnetic parameters. A significant difference between the perpendicular magnetic anisotropy constant in double ferromagnetic layer systems conduces to the decline of the interlayer interactions and different dispersion relations for the spin-wave modes. Our study provides a significant contribution to the realization of the multifunctional nonreciprocal magnonic devices based on ultrathin ferromagnetic/heavy-metal layer systems. |
| 8. | Krzysztof Sobucki, Wojciech Śmigaj, Justyna Rychły, Maciej Krawczyk, Paweł Gruszecki Sci. Rep., 11 (1), pp. 4428, 2021, ISSN: 2045-2322. @article{sobucki_resonant_2021, title = {Resonant subwavelength control of the phase of spin waves reflected from a Gires–Tournois interferometer}, author = {Krzysztof Sobucki and Wojciech Śmigaj and Justyna Rychły and Maciej Krawczyk and Paweł Gruszecki}, url = {https://www.nature.com/articles/s41598-021-83307-9}, doi = {10.1038/s41598-021-83307-9}, issn = {2045-2322}, year = {2021}, date = {2021-02-24}, urldate = {2021-02-25}, journal = {Sci. Rep.}, volume = {11}, number = {1}, pages = {4428}, abstract = {Subwavelength resonant elements are essential building blocks of metamaterials and metasurfaces, which have revolutionized photonics. Despite similarities between different wave phenomena, other types of interactions can make subwavelength coupling significantly distinct; its investigation in their context is therefore of interest both from the physics and applications perspective. In this work, we demonstrate a fully magnonic Gires–Tournois interferometer based on a subwavelength resonator made of a narrow ferromagnetic stripe lying above the edge of a ferromagnetic film. The bilayer formed by the stripe and the film underneath supports two propagative spin-wave modes, one strongly coupled with spin waves propagating in the rest of the film and another almost completely reflected at the ends of the bilayer. When the Fabry–Perot resonance conditions for this mode are satisfied, the weak coupling between both modes is sufficient to achieve high sensitivity of the phase of waves reflected from the resonator to the stripe width and, more interestingly, also to the stripe-film separation. Such spin-wave phase manipulation capabilities are a prerequisite for the design of spin-wave metasurfaces and may stimulate development of magnonic logic devices and sensors detecting magnetic nanoparticles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Subwavelength resonant elements are essential building blocks of metamaterials and metasurfaces, which have revolutionized photonics. Despite similarities between different wave phenomena, other types of interactions can make subwavelength coupling significantly distinct; its investigation in their context is therefore of interest both from the physics and applications perspective. In this work, we demonstrate a fully magnonic Gires–Tournois interferometer based on a subwavelength resonator made of a narrow ferromagnetic stripe lying above the edge of a ferromagnetic film. The bilayer formed by the stripe and the film underneath supports two propagative spin-wave modes, one strongly coupled with spin waves propagating in the rest of the film and another almost completely reflected at the ends of the bilayer. When the Fabry–Perot resonance conditions for this mode are satisfied, the weak coupling between both modes is sufficient to achieve high sensitivity of the phase of waves reflected from the resonator to the stripe width and, more interestingly, also to the stripe-film separation. Such spin-wave phase manipulation capabilities are a prerequisite for the design of spin-wave metasurfaces and may stimulate development of magnonic logic devices and sensors detecting magnetic nanoparticles. |
| 7. | Paweł Gruszecki, Igor L. Lyubchanskii, Konstantin Y Guslienko, Maciej Krawczyk Appl. Phys. Lett., 118 (6), pp. 062408, 2021. @article{doi:10.1063/5.0041030, title = {Local non-linear excitation of sub-100 nm bulk-type spin waves by edge-localized spin waves in magnetic films}, author = {Paweł Gruszecki and Igor L. Lyubchanskii and Konstantin Y Guslienko and Maciej Krawczyk}, doi = {10.1063/5.0041030}, year = {2021}, date = {2021-02-11}, journal = {Appl. Phys. Lett.}, volume = {118}, number = {6}, pages = {062408}, abstract = {The excitation of high-frequency short-wavelength spin waves is a challenge limiting the application of these propagating magnetization disturbances in information processing systems. We propose a method of local excitation of the high-frequency spin waves using the non-linear nature of magnetization dynamics. We demonstrate with numeric simulations that an edge-localized spin wave can be used to excite plane waves propagating obliquely from the film's edge at a doubled frequency and over twice shorter in wavelength. The excitation mechanism is a direct result of the ellipticity of the magnetic moment precession that is related to the edge-mode propagation. As a consequence, the magnetization component tangential to the equilibrium orientation oscillates with doubled temporal and spatial frequencies, which leads to efficient excitation of the plane spin waves. The threshold-less non-linear process of short-wavelength spin-wave excitation proposed in our study is promising for integration with an inductive or point-like spin-torque source of edge spin waves. The research leading to these results received funding from the National Science Centre of Poland, Project No. 2019/35/D/ST3/03729. I.L.L. acknowledges support from a COST action under Project No. CA17123 MAGNETOFON. K.Y.G. acknowledges support from IKERBASQUE (the Basque Foundation for Science) and from the Spanish Ministerio de Ciencia, Innovacion y Universidades Grant No. PID2019-108075RB-C33/AEI/10.13039/501100011033. The simulations were partially performed at the Poznan Supercomputing and Networking Center (Grant No. 398).}, keywords = {}, pubstate = {published}, tppubtype = {article} } The excitation of high-frequency short-wavelength spin waves is a challenge limiting the application of these propagating magnetization disturbances in information processing systems. We propose a method of local excitation of the high-frequency spin waves using the non-linear nature of magnetization dynamics. We demonstrate with numeric simulations that an edge-localized spin wave can be used to excite plane waves propagating obliquely from the film's edge at a doubled frequency and over twice shorter in wavelength. The excitation mechanism is a direct result of the ellipticity of the magnetic moment precession that is related to the edge-mode propagation. As a consequence, the magnetization component tangential to the equilibrium orientation oscillates with doubled temporal and spatial frequencies, which leads to efficient excitation of the plane spin waves. The threshold-less non-linear process of short-wavelength spin-wave excitation proposed in our study is promising for integration with an inductive or point-like spin-torque source of edge spin waves. The research leading to these results received funding from the National Science Centre of Poland, Project No. 2019/35/D/ST3/03729. I.L.L. acknowledges support from a COST action under Project No. CA17123 MAGNETOFON. K.Y.G. acknowledges support from IKERBASQUE (the Basque Foundation for Science) and from the Spanish Ministerio de Ciencia, Innovacion y Universidades Grant No. PID2019-108075RB-C33/AEI/10.13039/501100011033. The simulations were partially performed at the Poznan Supercomputing and Networking Center (Grant No. 398). |
| 6. | Jarosław W. Kłos, Igor L. Lyubchanskii, Maciej Krawczyk, Paweł Gruszecki, Szymon Mieszczak, Justyna Rychły, Yuliya S. Dadoenkova, Nataliya N. Dadoenkova Magnonics and Confinement of Light in Photonic–Magnonic Crystals, in Optomagnonic Structures Almpanis, Evangelos (Ed.): Chapter 2, pp. 79–134, World Scientific Publishing, Singapure, 2021, ISBN: 978-981-122-005-0. @inbook{opto-mag, title = {Magnonics and Confinement of Light in Photonic–Magnonic Crystals, in Optomagnonic Structures}, author = {Jarosław W. Kłos and Igor L. Lyubchanskii and Maciej Krawczyk and Paweł Gruszecki and Szymon Mieszczak and Justyna Rychły and Yuliya S. Dadoenkova and Nataliya N. Dadoenkova}, editor = {Evangelos Almpanis}, doi = {10.1142/9789811220050_0002}, isbn = {978-981-122-005-0}, year = {2021}, date = {2021-02-08}, pages = {79–134}, publisher = {World Scientific Publishing}, address = {Singapure}, chapter = {2}, abstract = {We discuss the spin-wave confinement in the magnetic components of magnetophotonic structures. In the initial sections of the chapter, we describe the principles of magnetization dynamics, including both the exchange and dipolar interactions. We showed that the spin-wave spectrum in confined geometry is determined not only by the spatial constraints but is also strongly influenced by non-local demagnetizing effects. In addition, we analyze the localization of light in the regions of spin-wave confinement, which can strengthen the magneto–optical interaction. Such enhancement can be potentially realized in photonic–magnonic crystals, where the light localization in magnetic components of the structure results from the periodicity and the spin waves co-exist with electromagnetic waves. The final sections are devoted to the Faraday effect and Goos–Hänchen effect in photonic–magnonic crystals.}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } We discuss the spin-wave confinement in the magnetic components of magnetophotonic structures. In the initial sections of the chapter, we describe the principles of magnetization dynamics, including both the exchange and dipolar interactions. We showed that the spin-wave spectrum in confined geometry is determined not only by the spatial constraints but is also strongly influenced by non-local demagnetizing effects. In addition, we analyze the localization of light in the regions of spin-wave confinement, which can strengthen the magneto–optical interaction. Such enhancement can be potentially realized in photonic–magnonic crystals, where the light localization in magnetic components of the structure results from the periodicity and the spin waves co-exist with electromagnetic waves. The final sections are devoted to the Faraday effect and Goos–Hänchen effect in photonic–magnonic crystals. |
| 5. | Nick Träger, Paweł Gruszecki, Filip Lisiecki, Felix Groß, Johannes Förster, Markus Weigand, Hubert Głowiński, Piotr Kuświk, Janusz Dubowik, Gisela Schütz, Maciej Krawczyk, Joachim Gräfe Real-Space Observation of Magnon Interaction with Driven Space-Time Crystals Phys. Rev. Lett., 126 , pp. 057201, 2021. @article{PhysRevLett.126.057201, title = {Real-Space Observation of Magnon Interaction with Driven Space-Time Crystals}, author = {Nick Träger and Paweł Gruszecki and Filip Lisiecki and Felix Groß and Johannes Förster and Markus Weigand and Hubert Głowiński and Piotr Kuświk and Janusz Dubowik and Gisela Schütz and Maciej Krawczyk and Joachim Gräfe}, url = {https://doi.org/10.1103/PhysRevLett.126.057201}, doi = {10.1103/PhysRevLett.126.057201}, year = {2021}, date = {2021-02-03}, journal = {Phys. Rev. Lett.}, volume = {126}, pages = {057201}, abstract = {The concept of space-time crystals (STC), i.e., translational symmetry breaking in time and space, was recently proposed and experimentally demonstrated for quantum systems. Here, we transfer this concept to magnons and experimentally demonstrate a driven STC at room temperature. The STC is realized by strong homogeneous microwave pumping of a micron-sized permalloy (Py) stripe and is directly imaged by scanning transmission x-ray microscopy (STXM). For a fundamental understanding of the formation of the STC, micromagnetic simulations are carefully adapted to model the experimental findings. Beyond the mere generation of a STC, we observe the formation of a magnonic band structure due to back folding of modes at the STC’s Brillouin zone boundaries. We show interactions of magnons with the STC that appear as lattice scattering, which results in the generation of ultrashort spin waves (SW) down to 100-nm wavelengths that cannot be described by classical dispersion relations for linear SW excitation. We expect that room-temperature STCs will be useful to investigate nonlinear wave physics, as they can be easily generated and manipulated to control their spatial and temporal band structures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The concept of space-time crystals (STC), i.e., translational symmetry breaking in time and space, was recently proposed and experimentally demonstrated for quantum systems. Here, we transfer this concept to magnons and experimentally demonstrate a driven STC at room temperature. The STC is realized by strong homogeneous microwave pumping of a micron-sized permalloy (Py) stripe and is directly imaged by scanning transmission x-ray microscopy (STXM). For a fundamental understanding of the formation of the STC, micromagnetic simulations are carefully adapted to model the experimental findings. Beyond the mere generation of a STC, we observe the formation of a magnonic band structure due to back folding of modes at the STC’s Brillouin zone boundaries. We show interactions of magnons with the STC that appear as lattice scattering, which results in the generation of ultrashort spin waves (SW) down to 100-nm wavelengths that cannot be described by classical dispersion relations for linear SW excitation. We expect that room-temperature STCs will be useful to investigate nonlinear wave physics, as they can be easily generated and manipulated to control their spatial and temporal band structures. |
| 4. | Nick Träger, Filip Lisiecki, Robert Lawitzki, Markus Weigand, Hubert Głowiński, Gisela Schütz, Guido Schmitz, Piotr Kuświk, Maciej Krawczyk, Joachim Gräfe, Paweł Gruszecki Competing spin wave emission mechanisms revealed by time-resolved x-ray microscopy Phys. Rev. B, 103 , pp. 014430, 2021. @article{PhysRevB.103.014430, title = {Competing spin wave emission mechanisms revealed by time-resolved x-ray microscopy}, author = {Nick Träger and Filip Lisiecki and Robert Lawitzki and Markus Weigand and Hubert Głowiński and Gisela Schütz and Guido Schmitz and Piotr Kuświk and Maciej Krawczyk and Joachim Gräfe and Paweł Gruszecki}, url = {https://link.aps.org/doi/10.1103/PhysRevB.103.014430}, doi = {10.1103/PhysRevB.103.014430}, year = {2021}, date = {2021-01-19}, journal = {Phys. Rev. B}, volume = {103}, pages = {014430}, publisher = {American Physical Society}, abstract = {Spin wave emission and propagation in magnonic waveguides represent a highly promising alternative for beyond-CMOS computing. It is therefore all the more important to fully understand the underlying physics of the emission process. Here, we use time-resolved scanning transmission x-ray microscopy to directly image the formation process of the globally excited local emission of spin waves in a permalloy waveguide at the nanoscale. Thereby, we observe spin wave emission from the corner of the waveguide as well as from a local oscillation of a domain-wall-like structure within the waveguide. Additionally, an isofrequency contour analysis is used to fully explain the origin of quasicylindrical spin wave excitation from the corner and its concurrent nonreflection and nonrefraction at the domain interface. This study is complemented by micromagnetic simulations which perfectly fit the experimental findings. Thus, we clarify the fundamental question of the emission mechanisms in magnonic waveguides which lay the basis for future magnonic operations.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spin wave emission and propagation in magnonic waveguides represent a highly promising alternative for beyond-CMOS computing. It is therefore all the more important to fully understand the underlying physics of the emission process. Here, we use time-resolved scanning transmission x-ray microscopy to directly image the formation process of the globally excited local emission of spin waves in a permalloy waveguide at the nanoscale. Thereby, we observe spin wave emission from the corner of the waveguide as well as from a local oscillation of a domain-wall-like structure within the waveguide. Additionally, an isofrequency contour analysis is used to fully explain the origin of quasicylindrical spin wave excitation from the corner and its concurrent nonreflection and nonrefraction at the domain interface. This study is complemented by micromagnetic simulations which perfectly fit the experimental findings. Thus, we clarify the fundamental question of the emission mechanisms in magnonic waveguides which lay the basis for future magnonic operations. |
| 3. | Ataollah Kalantari Osgouei, Hodjat Hajian, Bahram Khalichi, Andriy E. Serebryannikov, Amir Ghobadi, Ekmel Ozbay Active Tuning from Narrowband to Broadband Absorbers Using a Sub-wavelength VO2 Embedded Layer Plasmonics, 2021, ISSN: 1557-1963. @article{kalantari_osgouei_active_2021, title = {Active Tuning from Narrowband to Broadband Absorbers Using a Sub-wavelength VO2 Embedded Layer}, author = {Ataollah Kalantari Osgouei and Hodjat Hajian and Bahram Khalichi and Andriy E. Serebryannikov and Amir Ghobadi and Ekmel Ozbay}, url = {https://doi.org/10.1007/s11468-020-01370-w}, doi = {10.1007/s11468-020-01370-w}, issn = {1557-1963}, year = {2021}, date = {2021-01-18}, urldate = {2021-06-11}, journal = {Plasmonics}, abstract = {Metamaterial perfect absorbers (MPAs) with dynamic thermal tuning features are able to control the absorption performance of the resonances, providing diverse applications spanning from optical switches and filters to modulators. In this paper, we propose an MPA with diverse functionalities enabled by vanadium dioxide (VO2) embedded in a metal-dielectric plasmonic structure. For the initial design purpose, a silicon (Si) nanograting on a silver (Ag) mirror is proposed to have multiple resonant responses in the near infrared (NIR) region. Then, the insertion of a thin VO2 layer at the right position enables the design to act as an on/off switch and resonance tuner. In the insulator phase of VO2, in which the permittivity data of VO2 is similar to that of Si, a double strong resonant behavior is achieved within the NIR region. By increasing the temperature, the state of VO2 transforms from insulator to metallic so that the absorption bands turn into three distinct resonant peaks with close spectral positions. Upon this transformation, a new resonance emerges and the existing resonance features experience blue/red shifts in the spectral domain. The superposition of these peaks makes the overall absorption bandwidth broad. Although Si has a small thermo-optic coefficient, owing to strong light confinement in the ultrasmall gaps, a substantial tuning can be achieved within the Si nanogratings. Therefore, the proposed hybrid design can provide multi-resonance tunable features to cover a broad range and can be a promising strategy for the design of linearly thermal-tunable and broadband MPAs. Owing to the proposed double tuning feature, the resonance wavelengths exhibits great sensitivity to temperature, covering a broad wavelength range$$.$$Overall, the proposed design strategy demonstrates diverse functionalities enabled by the integration of a thin VO2 layer with plasmonic absorbers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metamaterial perfect absorbers (MPAs) with dynamic thermal tuning features are able to control the absorption performance of the resonances, providing diverse applications spanning from optical switches and filters to modulators. In this paper, we propose an MPA with diverse functionalities enabled by vanadium dioxide (VO2) embedded in a metal-dielectric plasmonic structure. For the initial design purpose, a silicon (Si) nanograting on a silver (Ag) mirror is proposed to have multiple resonant responses in the near infrared (NIR) region. Then, the insertion of a thin VO2 layer at the right position enables the design to act as an on/off switch and resonance tuner. In the insulator phase of VO2, in which the permittivity data of VO2 is similar to that of Si, a double strong resonant behavior is achieved within the NIR region. By increasing the temperature, the state of VO2 transforms from insulator to metallic so that the absorption bands turn into three distinct resonant peaks with close spectral positions. Upon this transformation, a new resonance emerges and the existing resonance features experience blue/red shifts in the spectral domain. The superposition of these peaks makes the overall absorption bandwidth broad. Although Si has a small thermo-optic coefficient, owing to strong light confinement in the ultrasmall gaps, a substantial tuning can be achieved within the Si nanogratings. Therefore, the proposed hybrid design can provide multi-resonance tunable features to cover a broad range and can be a promising strategy for the design of linearly thermal-tunable and broadband MPAs. Owing to the proposed double tuning feature, the resonance wavelengths exhibits great sensitivity to temperature, covering a broad wavelength range$$.$$Overall, the proposed design strategy demonstrates diverse functionalities enabled by the integration of a thin VO2 layer with plasmonic absorbers. |
| 2. | Nandan K. P. Babu, Aleksandra Trzaskowska, Piotr Graczyk, Grzegorz Centała, Szymon Mieszczak, Hubert Głowiński, Miłosz Zdunek, Sławomir Mielcarek, Jarosław W. Kłos Nano Lett., 21 (2), pp. 946-951, 2021. @article{doi:10.1021/acs.nanolett.0c03692, title = {The Interaction between Surface Acoustic Waves and Spin Waves: The Role of Anisotropy and Spatial Profiles of the Modes}, author = {Nandan K. P. Babu and Aleksandra Trzaskowska and Piotr Graczyk and Grzegorz Centała and Szymon Mieszczak and Hubert Głowiński and Miłosz Zdunek and Sławomir Mielcarek and Jarosław W. Kłos}, url = {https://doi.org/10.1021/acs.nanolett.0c03692}, doi = {10.1021/acs.nanolett.0c03692}, year = {2021}, date = {2021-01-01}, journal = {Nano Lett.}, volume = {21}, number = {2}, pages = {946-951}, abstract = {The interaction between different types of wave excitation in hybrid systems is usually anisotropic. Magnetoelastic coupling between surface acoustic waves and spin waves strongly depends on the direction of the external magnetic field. However, in the present study we observe that even if the orientation of the field is supportive for the coupling, the magnetoelastic interaction can be significantly reduced for surface acoustic waves with a particular profile in the direction normal to the surface at distances much smaller than the wavelength. We use Brillouin light scattering for the investigation of thermally excited phonons and magnons in a magnetostrictive CoFeB/Au multilayer deposited on a Si substrate. The experimental data are interpreted on the basis of a linearized model of interaction between surface acoustic waves and spin waves.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The interaction between different types of wave excitation in hybrid systems is usually anisotropic. Magnetoelastic coupling between surface acoustic waves and spin waves strongly depends on the direction of the external magnetic field. However, in the present study we observe that even if the orientation of the field is supportive for the coupling, the magnetoelastic interaction can be significantly reduced for surface acoustic waves with a particular profile in the direction normal to the surface at distances much smaller than the wavelength. We use Brillouin light scattering for the investigation of thermally excited phonons and magnons in a magnetostrictive CoFeB/Au multilayer deposited on a Si substrate. The experimental data are interpreted on the basis of a linearized model of interaction between surface acoustic waves and spin waves. |
| 1. | Sławomir Mielcarek, A. Majchrowski Growth of ABO3 and BO2 crystals (in book: Switching effects in transition metals oxides) Szot, K S, Krok, F, Roleder, K (Ed.): Chapter 2, PWN, 2021. @inbook{switching_effects, title = {Growth of ABO3 and BO2 crystals (in book: Switching effects in transition metals oxides)}, author = {Sławomir Mielcarek and A. Majchrowski}, editor = {K. S. Szot and F. Krok and K. Roleder}, year = {2021}, date = {2021-01-01}, publisher = {PWN}, chapter = {2}, abstract = {Structural quality as well as stoichiometry of crystalline materials are the main factors influencing their physical properties, and therefore decide on their potential applications. Bulk crystallization of many oxide perovskites suffers from many drawbacks due to properties of melts, existing high-temperature phase transitions, and non-stoichiometry, among others. However, tremendous progress in thin-film and other structure technologies allows, mainly due to vapor techniques, fabrication of high-quality samples for further investigations and applications. Understanding of thermodynamics and kinetics of crystal growth, nucleation processes, and knowledge of proper crystal growth techniques is essential to obtain good quality crystals. The chapter is mainly devoted to crystal growth techniques of chosen oxide crystals. The theory of crystal growth, due to limited space, is described in short. Given references will allow the reader a full view into its complexity and many aspects of phenomena connected with crystallization. In the last part of the chapter methods of analysis of as-grown crystals are described.}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } Structural quality as well as stoichiometry of crystalline materials are the main factors influencing their physical properties, and therefore decide on their potential applications. Bulk crystallization of many oxide perovskites suffers from many drawbacks due to properties of melts, existing high-temperature phase transitions, and non-stoichiometry, among others. However, tremendous progress in thin-film and other structure technologies allows, mainly due to vapor techniques, fabrication of high-quality samples for further investigations and applications. Understanding of thermodynamics and kinetics of crystal growth, nucleation processes, and knowledge of proper crystal growth techniques is essential to obtain good quality crystals. The chapter is mainly devoted to crystal growth techniques of chosen oxide crystals. The theory of crystal growth, due to limited space, is described in short. Given references will allow the reader a full view into its complexity and many aspects of phenomena connected with crystallization. In the last part of the chapter methods of analysis of as-grown crystals are described. |