Dr hab. Anna Dyrdał, prof. UAM
Head of Department of Mesoscopic Physics
- Tel: +48 61 829 5288
- Loc: wing J, 2nd floor, room 207
- Email: adyrdal@amu.edu.pl
Scientific degrees
Habilitation – 2020
PhD in physics – 2013
MSc in physics – 2009
Research interests
Keywords: spintronics, electron and spin transport, spin-orbit driven phenomena, Hall effect, spin current, magnetoresistance, topological insulators, graphene, semiconductor heterostructures
Research stays
2019 – Unité Mixte de Physique CNRS/Thales, Palaiseau, France
2017 – 2019 Martin-Luther-Universität, Halle, Germany
2015 – Universidad del Pais Vasco, UPV/EHU Bilbao, Spain
Scientific achievements
2020 – Fellowship of the Polish Ministry of Science and Higher Education for outstanding young scientists
2019 – French Government Scholarship
2016 – Scholarship START of The Foundation for Polish Science (FNP)
2014 – Scholarship for young scientists granted by the city of Poznań
2012 – Scholarship of the Foundation of A. Mickiewicz University in Poznań
2009 – Arkadiusz Piekara Award of the Polish Physical Society
Rector’s awards for scientific research (A. Mickiewicz University in Poznań)
Projects
| 2. | Anna Dyrdał Spin and charge transport in low-dimensional novel quantum materials (2Dtronics) 2020 - 2023, (NCN GRIEG, No. 2019/34/H/ST3/00515, budget: 5 816 151,00 PLN ). @misc{2Dtronics, title = {Spin and charge transport in low-dimensional novel quantum materials (2Dtronics)}, author = {Anna Dyrdał}, url = {http://2dtronics.amu.edu.pl}, year = {2023}, date = {2023-09-30}, abstract = { 2Dtronics is focused on selected aspects of fundamental solid-state physics and magnetism, which may support the main concept of spintronics: efficient control of the spin state and its utilization on equal footing with quasiparticle charge. In principle, we focus on such subfields of spin electronics as spin-orbitronics, magnonics, and antiferromagnetic spintronics, where the symmetries and topological properties of the systems play an essential role. We wish to focus on novel materials that may serve as a platform for phenomena where the topological nature of quasiparticle states plays an essential role and which allow for a variety of spin-to-charge interconversion phenomena. We wish to combine altogether the spin and valley degrees of freedom with the symmetries and topological properties of the system to describe and propose phenomena that enable us to work out new protocols for electronic and logic devices. Additionally, we want to study the presence of some emergent phenomena in low dimensional quantum magnetic systems, like magnon Bose-Einstein condensation and spin superfluidity, which are important from both academic and application points of view. Another important question that we address in this proposal is the effect of many-body interactions in low dimensional magnetic quantum materials. In principle, we intend to focus on theoretical models that reveal: topological invariant or topological charge, non-zero Berry curvature dipole, desired symmetry properties, experimentally tunable parameters. }, howpublished = {2020}, note = {NCN GRIEG, No. 2019/34/H/ST3/00515, budget: 5 816 151,00 PLN }, keywords = {}, pubstate = {published}, tppubtype = {misc} } 2Dtronics is focused on selected aspects of fundamental solid-state physics and magnetism, which may support the main concept of spintronics: efficient control of the spin state and its utilization on equal footing with quasiparticle charge. In principle, we focus on such subfields of spin electronics as spin-orbitronics, magnonics, and antiferromagnetic spintronics, where the symmetries and topological properties of the systems play an essential role. We wish to focus on novel materials that may serve as a platform for phenomena where the topological nature of quasiparticle states plays an essential role and which allow for a variety of spin-to-charge interconversion phenomena. We wish to combine altogether the spin and valley degrees of freedom with the symmetries and topological properties of the system to describe and propose phenomena that enable us to work out new protocols for electronic and logic devices. Additionally, we want to study the presence of some emergent phenomena in low dimensional quantum magnetic systems, like magnon Bose-Einstein condensation and spin superfluidity, which are important from both academic and application points of view. Another important question that we address in this proposal is the effect of many-body interactions in low dimensional magnetic quantum materials. In principle, we intend to focus on theoretical models that reveal: topological invariant or topological charge, non-zero Berry curvature dipole, desired symmetry properties, experimentally tunable parameters. |
| 1. | Anna Dyrdał 2019 - 2022, (NCN Sonata 14, No. 2018/31/D/ST3/02351, budget: 711 820,00 PLN). @misc{Dyrdał2019, title = {Theoretical study of the magnetoresistance phenomena in 2D structures with strong spin-orbit interaction}, author = {Anna Dyrdał}, url = {http://zfmezo.home.amu.edu.pl/Sonata14.php}, year = {2022}, date = {2022-02-01}, howpublished = {2019}, note = {NCN Sonata 14, No. 2018/31/D/ST3/02351, budget: 711 820,00 PLN}, keywords = {}, pubstate = {published}, tppubtype = {misc} } |
Publications
2024 |
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| 28. | Anna Krzyżewska, Anna Dyrdał physica status solidi (RRL) – Rapid Research Letters, 18 (12), pp. 2400123, 2024, ISSN: 1862-6254. @article{Krzyzewska2024Jun, title = {Nonlinear Hall Effect in Isotropic k-Cubed Rashba Model: Berry-Curvature-Dipole Engineering by In-Plane Magnetic Field}, author = {Anna Krzyżewska and Anna Dyrdał}, url = {https://onlinelibrary.wiley.com/doi/10.1002/pssr.202400123 https://arxiv.org/abs/2404.07352}, doi = {10.1002/pssr.202400123}, issn = {1862-6254}, year = {2024}, date = {2024-12-03}, journal = {physica status solidi (RRL) – Rapid Research Letters}, volume = {18}, number = {12}, pages = {2400123}, abstract = {The linear and nonlinear Hall effects in 2D electron gas are considered theoretically within the isotropic k-cubed Rashba model. It is shown that the presence of an out-of-plane external magnetic field or net magnetization is a necessary condition to induce a nonzero Berry curvature in the system, whereas an in-plane magnetic field tunes the Berry curvature leading to the Berry curvature dipole. Interestingly, in the linear response regime, the conductivity is dominated by the intrinsic component (Berry curvature component), whereas the second-order correction to the Hall current (i.e., the conductivity proportional to the external electric field) is dominated by the component independent of the Berry curvature dipole.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The linear and nonlinear Hall effects in 2D electron gas are considered theoretically within the isotropic k-cubed Rashba model. It is shown that the presence of an out-of-plane external magnetic field or net magnetization is a necessary condition to induce a nonzero Berry curvature in the system, whereas an in-plane magnetic field tunes the Berry curvature leading to the Berry curvature dipole. Interestingly, in the linear response regime, the conductivity is dominated by the intrinsic component (Berry curvature component), whereas the second-order correction to the Hall current (i.e., the conductivity proportional to the external electric field) is dominated by the component independent of the Berry curvature dipole. |
| 27. | Stefan Stagraczyński, Pavel Baláž, Mirali Jafari, Józef Barnaś, Anna Dyrdał Scientific Reports, 14 , pp. 25552, 2024. @article{Stagraczynski2024, title = {Magnetic ordering and dynamics in monolayers and bilayers of chromium trihalides: atomistic simulations approach}, author = {Stefan Stagraczyński and Pavel Baláž and Mirali Jafari and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1038/s41598-024-75501-2}, doi = {10.1038/s41598-024-75501-2}, year = {2024}, date = {2024-10-26}, journal = {Scientific Reports}, volume = {14}, pages = {25552}, abstract = {We analyze magnetic properties of monolayers and bilayers of chromium iodide, CrI3, in two different stacking configurations: AA and rhombohedral ones. Our main focus is on the corresponding Curie temperatures, hysteresis curves, equilibrium spin structures, and spin wave excitations. To obtain all these magnetic characteristic, we employ the atomistic spin dynamics and Monte Carlo simulation techniques. The model Hamiltonian includes isotropic exchange coupling, magnetic anisotropy, and Dzyaloshinskii-Moriya interaction. As the latter interaction is relatively weak in pristine CrI3, we consider a more general case, when the Dzyaloshinskii-Moriya interaction is enhanced externally (e.g. due to gate voltage, mechanical strain, or proximity effects). An important issue of the analysis is the correlation between hysteresis curves and spin configurations in the system, as well as formation of the skyrmion textures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We analyze magnetic properties of monolayers and bilayers of chromium iodide, CrI3, in two different stacking configurations: AA and rhombohedral ones. Our main focus is on the corresponding Curie temperatures, hysteresis curves, equilibrium spin structures, and spin wave excitations. To obtain all these magnetic characteristic, we employ the atomistic spin dynamics and Monte Carlo simulation techniques. The model Hamiltonian includes isotropic exchange coupling, magnetic anisotropy, and Dzyaloshinskii-Moriya interaction. As the latter interaction is relatively weak in pristine CrI3, we consider a more general case, when the Dzyaloshinskii-Moriya interaction is enhanced externally (e.g. due to gate voltage, mechanical strain, or proximity effects). An important issue of the analysis is the correlation between hysteresis curves and spin configurations in the system, as well as formation of the skyrmion textures. |
| 26. | Izabella Wojciechowska, Anna Dyrdał Intrinsic anomalous, spin and valley Hall effects in ’ex-so-tic’ van-der-Waals structures Scientific Reports, 14 , pp. 23808, 2024. @article{Wojciechowska2024, title = {Intrinsic anomalous, spin and valley Hall effects in ’ex-so-tic’ van-der-Waals structures}, author = {Izabella Wojciechowska and Anna Dyrdał }, url = {https://doi.org/10.1038/s41598-024-74596-x}, doi = {10.1038/s41598-024-74596-x}, year = {2024}, date = {2024-10-11}, journal = {Scientific Reports}, volume = {14}, pages = {23808}, abstract = {We consider the anomalous, spin, valley, and valley spin Hall effects in a pristine graphene-based van-der-Waals (vdW) heterostructure consisting of a bilayer graphene (BLG) sandwiched between a semiconducting van-der-Waals material with strong spin-orbit coupling (e.g., WS2) and a ferromagnetic insulating vdW material (e.g. Cr2Ge2Te2). Due to the exchange proximity effect from one side and spin-orbit proximity effect from the other side of graphene, such a structure is referred to as graphene based ’ex-so-tic’ structure. First, we derive an effective Hamiltonian describing the low-energy states of the structure. Then, using the Green’s function formalism, we obtain analytical results for the Hall conductivities as a function of the Fermi energy and gate voltage. For specific values of these parameters, we find a quantized valley Hall conductivity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We consider the anomalous, spin, valley, and valley spin Hall effects in a pristine graphene-based van-der-Waals (vdW) heterostructure consisting of a bilayer graphene (BLG) sandwiched between a semiconducting van-der-Waals material with strong spin-orbit coupling (e.g., WS2) and a ferromagnetic insulating vdW material (e.g. Cr2Ge2Te2). Due to the exchange proximity effect from one side and spin-orbit proximity effect from the other side of graphene, such a structure is referred to as graphene based ’ex-so-tic’ structure. First, we derive an effective Hamiltonian describing the low-energy states of the structure. Then, using the Green’s function formalism, we obtain analytical results for the Hall conductivities as a function of the Fermi energy and gate voltage. For specific values of these parameters, we find a quantized valley Hall conductivity. |
| 25. | Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Journal of Magnetism and Magnetic Materials, 606 , pp. 172321, 2024. @article{Rudzinski2024b, title = {Spin waves in antiferromagnetically coupled bilayers of transition-metal dichalcogenides with Dzyaloshinskii–Moriya interaction}, author = {Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1016/j.jmmm.2024.172321}, doi = {10.1016/j.jmmm.2024.172321}, year = {2024}, date = {2024-09-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {606}, pages = {172321}, abstract = {In this paper we analyse quantized spin waves (also referred to as magnons) in bilayers of two-dimensional van der Waals materials, like Vanadium-based dichalcogenides, VX2 (X = S, Se, Te) and other materials of similar symmetry. We assume that the materials exhibit Dzyaloshinskii–Moriya interaction and in-plane easy-axis magnetic anisotropy due to symmetry breaking induced externally (e.g. by strain, gate voltage, proximity effects to an appropriate substrate/oberlayer, etc.). The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong in-plane magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation. Accordingly, the description takes into account quantum antiferromagnetic fluctuations. However, it is limited to linear spinwave modes. The Dzyaloshinskii–Moriya interaction is shown to modify the spin wave spectrum of the bilayers, making its low energy part qualitatively similar to the electronic spectrum of the Rashba spin–orbit model.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this paper we analyse quantized spin waves (also referred to as magnons) in bilayers of two-dimensional van der Waals materials, like Vanadium-based dichalcogenides, VX2 (X = S, Se, Te) and other materials of similar symmetry. We assume that the materials exhibit Dzyaloshinskii–Moriya interaction and in-plane easy-axis magnetic anisotropy due to symmetry breaking induced externally (e.g. by strain, gate voltage, proximity effects to an appropriate substrate/oberlayer, etc.). The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong in-plane magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation. Accordingly, the description takes into account quantum antiferromagnetic fluctuations. However, it is limited to linear spinwave modes. The Dzyaloshinskii–Moriya interaction is shown to modify the spin wave spectrum of the bilayers, making its low energy part qualitatively similar to the electronic spectrum of the Rashba spin–orbit model. |
| 24. | Amir N. Zarezad, Alireza Qaiumzadeh, Józef Barnaś, Anna Dyrdał Topological charge and spin Hall effects due to skyrmions in canted antiferromagnets Physical Review B, 110 (5), pp. 054431, 2024. @article{Zarezad2024b, title = {Topological charge and spin Hall effects due to skyrmions in canted antiferromagnets}, author = {Amir N. Zarezad and Alireza Qaiumzadeh and Józef Barnaś and Anna Dyrdał }, url = {https://doi.org/10.1103/PhysRevB.110.054431}, doi = {10.1103/PhysRevB.110.054431}, year = {2024}, date = {2024-08-20}, journal = {Physical Review B}, volume = {110}, number = {5}, pages = {054431}, abstract = {The topological charge Hall effect (TCHE) and the topological spin Hall effect (TSHE), arising from ferromagnetic (FM) and antiferromagnetic (AFM) skyrmions, respectively, can be elucidated through the emergence of spin-dependent Berry gauge fields that affect the adiabatic flow of electrons within the skyrmion texture. TCHE is absent in systems with parity-time (PT) symmetry, such as collinear AFM systems. In this paper, we theoretically study TCHE and TSHE in a canted antiferromagnet within the diffusive transport regime. Spin canting or weak ferromagnetism in canted AFMs, which break the PT symmetry, may arise, e.g., from strong homogeneous Dzyaloshinskii-Moriya interactions. Using a semiclassical Boltzmann approach, we obtain diffusion equations for the spin and charge accumulations in the presence of finite spin flip and spin-dependent momentum relaxation times. We show that the weak ferromagnetic moment stemming from spin canting and the subsequent breaking of PT symmetry, results in the emergence of both finite TCHE and TSHE in AFM systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The topological charge Hall effect (TCHE) and the topological spin Hall effect (TSHE), arising from ferromagnetic (FM) and antiferromagnetic (AFM) skyrmions, respectively, can be elucidated through the emergence of spin-dependent Berry gauge fields that affect the adiabatic flow of electrons within the skyrmion texture. TCHE is absent in systems with parity-time (PT) symmetry, such as collinear AFM systems. In this paper, we theoretically study TCHE and TSHE in a canted antiferromagnet within the diffusive transport regime. Spin canting or weak ferromagnetism in canted AFMs, which break the PT symmetry, may arise, e.g., from strong homogeneous Dzyaloshinskii-Moriya interactions. Using a semiclassical Boltzmann approach, we obtain diffusion equations for the spin and charge accumulations in the presence of finite spin flip and spin-dependent momentum relaxation times. We show that the weak ferromagnetic moment stemming from spin canting and the subsequent breaking of PT symmetry, results in the emergence of both finite TCHE and TSHE in AFM systems. |
| 23. | Verena Brehm, Stefan Stagraczyński, Józef Barnaś, Anna Dyrdał, Alireza Qaiumzadeh Physical Review Materials, 8 (5), pp. 054002, 2024. @article{Brehm2024, title = {Magnon dispersion and spin transport in CrCl3 bilayers under different strain-induced magnetic states}, author = {Verena Brehm and Stefan Stagraczyński and Józef Barnaś and Anna Dyrdał and Alireza Qaiumzadeh}, url = {https://doi.org/10.1103/PhysRevMaterials.8.054002 }, doi = {10.1103/PhysRevMaterials.8.054002}, year = {2024}, date = {2024-05-03}, journal = {Physical Review Materials}, volume = {8}, number = {5}, pages = {054002}, abstract = {Atomically thin van der Waals magnetic materials offer exceptional opportunities to mechanically and electrically manipulate magnetic states and spin textures. The possibility of efficient spin transport in these materials makes them promising for the development of novel nanospintronics technology. Using atomistic spin dynamics simulations, we investigate magnetic ground state, magnon dispersion, critical temperature, and magnon spin transport in CrCl3 bilayers in the absence and presence of compressive and tensile strains. We show that in the presence of mechanical strain, the magnon band gap at the Γ point and the critical temperature of the bilayer are increased. Furthermore, our simulations show that the magnon diffusion length is reduced in the presence of strain. Moreover, by exciting magnons through the spin Seebeck effect and spin Hall-induced torque, we illustrate distinctions between magnon spin transport in the antiferromagnetic state, under compressive strains, and ferromagnetic states, under tensile strains or in the unstrained case.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Atomically thin van der Waals magnetic materials offer exceptional opportunities to mechanically and electrically manipulate magnetic states and spin textures. The possibility of efficient spin transport in these materials makes them promising for the development of novel nanospintronics technology. Using atomistic spin dynamics simulations, we investigate magnetic ground state, magnon dispersion, critical temperature, and magnon spin transport in CrCl3 bilayers in the absence and presence of compressive and tensile strains. We show that in the presence of mechanical strain, the magnon band gap at the Γ point and the critical temperature of the bilayer are increased. Furthermore, our simulations show that the magnon diffusion length is reduced in the presence of strain. Moreover, by exciting magnons through the spin Seebeck effect and spin Hall-induced torque, we illustrate distinctions between magnon spin transport in the antiferromagnetic state, under compressive strains, and ferromagnetic states, under tensile strains or in the unstrained case. |
| 22. | Michał Inglot, Józef Barnaś, Vitalii K. Dugaev, Anna Dyrdał Physical Review B, 109 (13), pp. 134435, 2024. @article{Inglot2024, title = {Localized states at the Rashba spin-orbit domain wall in magnetized graphene: Interplay of Rashba and magnetic domain walls}, author = {Michał Inglot and Józef Barnaś and Vitalii K. Dugaev and Anna Dyrdał}, url = {https://link.aps.org/doi/10.1103/PhysRevB.109.134435}, doi = {10.1103/PhysRevB.109.134435}, year = {2024}, date = {2024-04-23}, journal = {Physical Review B}, volume = {109}, number = {13}, pages = {134435}, abstract = {It is well known that electronic states in graphene with a uniform Rashba spin-orbit interaction and uniform magnetization, e.g., due to exchange coupling to a magnetic substrate, display an energy gap around the Dirac 𝐾 and 𝐾′ points. When the magnetization of graphene is nonuniform and forms a magnetic domain wall, electronic states localized at the wall emerge in the energy gap. In this paper we show that similar localized electronic states appear in the gap when the graphene is uniformly magnetized, while a domain wall appears in the Rashba spin-orbit interaction (i.e., opposite signs of the Rashba parameter on both sides of the wall). These electronic states propagate along the wall and are localized exponentially at the Rashba domain wall. They form narrow and nearly parabolic (at small wave vectors) bands, with relatively large effective electron mass. However, contrary to the magnetic domain wall, these states do not close the energy gap. We also consider the situation when the magnetic domain wall coexists with the Rashba domain wall, and both walls are localized at the same position. Electronic states due to the interplay of both domain walls are determined analytically and it is shown that the electronic states localized at the walls close the gap when a magnetic domain wall (symmetric or asymmetric) exists, independently of the Rashba parameter behavior.}, keywords = {}, pubstate = {published}, tppubtype = {article} } It is well known that electronic states in graphene with a uniform Rashba spin-orbit interaction and uniform magnetization, e.g., due to exchange coupling to a magnetic substrate, display an energy gap around the Dirac 𝐾 and 𝐾′ points. When the magnetization of graphene is nonuniform and forms a magnetic domain wall, electronic states localized at the wall emerge in the energy gap. In this paper we show that similar localized electronic states appear in the gap when the graphene is uniformly magnetized, while a domain wall appears in the Rashba spin-orbit interaction (i.e., opposite signs of the Rashba parameter on both sides of the wall). These electronic states propagate along the wall and are localized exponentially at the Rashba domain wall. They form narrow and nearly parabolic (at small wave vectors) bands, with relatively large effective electron mass. However, contrary to the magnetic domain wall, these states do not close the energy gap. We also consider the situation when the magnetic domain wall coexists with the Rashba domain wall, and both walls are localized at the same position. Electronic states due to the interplay of both domain walls are determined analytically and it is shown that the electronic states localized at the walls close the gap when a magnetic domain wall (symmetric or asymmetric) exists, independently of the Rashba parameter behavior. |
| 21. | Kateryna Boboshko, Anna Dyrdał Physical Review B, 109 (15), pp. 155420, 2024. @article{Boboshko2024, title = {Bilinear magnetoresistance and planar Hall effect in topological insulators: Interplay of scattering on spin-orbital impurities and nonequilibrium spin polarization}, author = {Kateryna Boboshko and Anna Dyrdał}, url = {https://link.aps.org/doi/10.1103/PhysRevB.109.155420}, doi = {10.1103/PhysRevB.109.155420}, year = {2024}, date = {2024-04-15}, journal = {Physical Review B}, volume = {109}, number = {15}, pages = {155420}, abstract = {We have considered theoretically nonlinear transport phenomena known as bilinear magnetoresistance (BMR) and nonlinear planar Hall effect (NPHE) within the effective model describing surface states of a 3D topological insulator. Both phenomena can occur in nonmagnetic materials with strong spin-orbit interaction and reveal a term that depends linearly on the charge current density (external electric field) and in-plane magnetic field. In earlier studies, the physical mechanism of BMR and NPHE was related to scattering on spin-momentum locking inhomogeneities or to the hexagonal warping of Dirac cones. Here, we focus on another mechanism related to scattering on impurities that inherently contain spin-orbit coupling. Using the Green's function formalism and diagramatic method, we have derived analytical results for diagonal and transverse conductivities and determined nonlinear signals. The analytical and numerical results on BMR and NPHE indicate the possibility of determining the material constants, such as the Fermi wave vector and spin-orbit coupling parameter, by simple magnetotransport measurements.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We have considered theoretically nonlinear transport phenomena known as bilinear magnetoresistance (BMR) and nonlinear planar Hall effect (NPHE) within the effective model describing surface states of a 3D topological insulator. Both phenomena can occur in nonmagnetic materials with strong spin-orbit interaction and reveal a term that depends linearly on the charge current density (external electric field) and in-plane magnetic field. In earlier studies, the physical mechanism of BMR and NPHE was related to scattering on spin-momentum locking inhomogeneities or to the hexagonal warping of Dirac cones. Here, we focus on another mechanism related to scattering on impurities that inherently contain spin-orbit coupling. Using the Green's function formalism and diagramatic method, we have derived analytical results for diagonal and transverse conductivities and determined nonlinear signals. The analytical and numerical results on BMR and NPHE indicate the possibility of determining the material constants, such as the Fermi wave vector and spin-orbit coupling parameter, by simple magnetotransport measurements. |
| 20. | Amir N. Zarezad, Józef Barnaś, Alireza Qaiumzadeh, Anna Dyrdał Bilinear Planar Hall Effect in Topological Insulators Due to Spin-Momentum Locking Inhomogeneity physica status solidi (RRL) – Rapid Research Letters, 18 (3), pp. 2200483, 2024. @article{Zarezad2024c, title = {Bilinear Planar Hall Effect in Topological Insulators Due to Spin-Momentum Locking Inhomogeneity}, author = {Amir N. Zarezad and Józef Barnaś and Alireza Qaiumzadeh and Anna Dyrdał}, url = {https://doi.org/10.1002/pssr.202200483}, doi = {10.1002/pssr.202200483}, year = {2024}, date = {2024-03-13}, journal = {physica status solidi (RRL) – Rapid Research Letters}, volume = {18}, number = {3}, pages = {2200483}, abstract = {Herein, the effect of spin-momentum locking inhomogeneity on the planar Hall effect in topological insulators (TIs) is studied. Using the minimal model describing surface states of 3D TIs and semiclassical Boltzmann formalism, the planar Hall conductivity (PHC) within the generalized relaxation time approximation is derived. Herein, it is found that the total PHC consists of linear and nonlinear (in electric field) components. The linear term is a conventional PHC which scales quadratically with an external magnetic field, whereas the nonlinear term reveals bilinear behavior, that is, changes its sign when either charge current density or in-plane magnetic-field orientation is reversed. It is shown that the emergent nonlinear planar Hall effect is a consequence of spin-momentum locking inhomogeneity in the TIs with isotropic energy dispersion, and dominates over the conventional planar Hall effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Herein, the effect of spin-momentum locking inhomogeneity on the planar Hall effect in topological insulators (TIs) is studied. Using the minimal model describing surface states of 3D TIs and semiclassical Boltzmann formalism, the planar Hall conductivity (PHC) within the generalized relaxation time approximation is derived. Herein, it is found that the total PHC consists of linear and nonlinear (in electric field) components. The linear term is a conventional PHC which scales quadratically with an external magnetic field, whereas the nonlinear term reveals bilinear behavior, that is, changes its sign when either charge current density or in-plane magnetic-field orientation is reversed. It is shown that the emergent nonlinear planar Hall effect is a consequence of spin-momentum locking inhomogeneity in the TIs with isotropic energy dispersion, and dominates over the conventional planar Hall effect. |
| 19. | Piotr Pigoń, Anna Dyrdał Journal of Magnetism and Magnetic Materials, 593 , pp. 171795, 2024. @article{Pigon2024, title = {Electronic and topological properties of a topological insulator sandwiched between ferromagnetic insulators}, author = {Piotr Pigoń and Anna Dyrdał }, url = {https://doi.org/10.1016/j.jmmm.2024.171795}, doi = {10.1016/j.jmmm.2024.171795}, year = {2024}, date = {2024-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {593}, pages = {171795}, abstract = {We consider a film of a topological insulator (TI) sandwiched between two ferromagnetic (FM) layers. The system is additionally under an external gate voltage. The surface electron states of TI are magnetized due to the magnetic proximity effect to the ferromagnetic layers. The magnetization of ferromagnetic layers can be changed by applying an external magnetic field or by varying thickness of the topological insulator (owing to the interlayer exchange coupling). The change in the magnetic configuration of the system affects the transport properties of the surface electronic states. Using the Green function formalism, we calculate spin polarization, anomalous Hall effect, and magnetoresistance of the system. We show, among others, that by tuning the gate voltage and magnetizations of the top and bottom FM layers, one can observe the topological transition to the quantum anomalous Hall state.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We consider a film of a topological insulator (TI) sandwiched between two ferromagnetic (FM) layers. The system is additionally under an external gate voltage. The surface electron states of TI are magnetized due to the magnetic proximity effect to the ferromagnetic layers. The magnetization of ferromagnetic layers can be changed by applying an external magnetic field or by varying thickness of the topological insulator (owing to the interlayer exchange coupling). The change in the magnetic configuration of the system affects the transport properties of the surface electronic states. Using the Green function formalism, we calculate spin polarization, anomalous Hall effect, and magnetoresistance of the system. We show, among others, that by tuning the gate voltage and magnetizations of the top and bottom FM layers, one can observe the topological transition to the quantum anomalous Hall state. |
| 18. | Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Spin waves in bilayers of transition metal dichalcogenides Physical Review B, 109 , pp. 035412, 2024. @article{Rudziński2024, title = {Spin waves in bilayers of transition metal dichalcogenides}, author = {Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.035412}, doi = {10.1103/PhysRevB.109.035412}, year = {2024}, date = {2024-01-11}, journal = {Physical Review B}, volume = {109}, pages = {035412}, abstract = {Van der Waals magnetic materials are currently of great interest as materials for applications in future ultrathin nanoelectronics and nanospintronics. Due to weak coupling between individual monolayers, these materials can be easily obtained in the monolayer and bilayer forms. The latter are of specific interest as they may be considered as natural two-dimensional spin valves. In this paper, we theoretically study spin waves in bilayers of transition metal dichalcogenides. The considerations are carried within the general spin wave theory based on effective spin Hamiltonian and Holstein-Primakoff-Bogolubov transformation. The spin Hamiltonian includes intralayer as well as interlayer nearest-neighbor exchange interactions, easy-plane anisotropy, and additionally a weak in-plane easy-axis anisotropy. The bilayer systems consist of two ferromagnetic (in-plane magnetization) monolayers that are coupled either ferromagnetically or antiferromagnetically. In the latter case, we analyze the spin-wave spectra in all magnetic phases, i.e., in the antiferromagnetic, spin-flop, and ferromagnetic ones.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Van der Waals magnetic materials are currently of great interest as materials for applications in future ultrathin nanoelectronics and nanospintronics. Due to weak coupling between individual monolayers, these materials can be easily obtained in the monolayer and bilayer forms. The latter are of specific interest as they may be considered as natural two-dimensional spin valves. In this paper, we theoretically study spin waves in bilayers of transition metal dichalcogenides. The considerations are carried within the general spin wave theory based on effective spin Hamiltonian and Holstein-Primakoff-Bogolubov transformation. The spin Hamiltonian includes intralayer as well as interlayer nearest-neighbor exchange interactions, easy-plane anisotropy, and additionally a weak in-plane easy-axis anisotropy. The bilayer systems consist of two ferromagnetic (in-plane magnetization) monolayers that are coupled either ferromagnetically or antiferromagnetically. In the latter case, we analyze the spin-wave spectra in all magnetic phases, i.e., in the antiferromagnetic, spin-flop, and ferromagnetic ones. |
| 17. | Amir N. Zarezad, Józef Barnaś, Anna Dyrdał, Alireza Qaiumzadeh Skyrmion-deriven topological spin and charge Hall effects in diffusive antiferromagnetic thin films Journal of Magnetism and Magnetic Materials, 589 , pp. 171599, 2024. @article{Zarezad2024, title = {Skyrmion-deriven topological spin and charge Hall effects in diffusive antiferromagnetic thin films}, author = {Amir N. Zarezad and Józef Barnaś and Anna Dyrdał and Alireza Qaiumzadeh}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323012490?via%3Dihub}, doi = {10.1016/j.jmmm.2023.171599}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = { 171599}, abstract = {We investigate topological Hall effects in a metallic antiferromagnetic (AFM) thin film and/or at the interface of an AFM insulator–normal metal bilayer with a single skyrmion in the diffusive regime. To determine the spin- and charge Hall currents, we employed a Boltzmann kinetic equation with both spin-dependent and spin-flip scatterings. The interaction between conduction electrons and static skyrmions is included in the Boltzmann equation via the corresponding emergent magnetic field arising from the skyrmion texture. We compute intrinsic and extrinsic contributions to the topological spin Hall effect and spin accumulation, induced by an AFM skyrmion. We show that although the spin Hall current vanishes rapidly outside the skyrmion, the spin accumulation can be finite at the edges far from the skyrmion, provided the spin diffusion length is longer than the skyrmion radius. In addition, We show that in the presence of a spin-dependent relaxation time, the topological charge Hall effect is finite and we determine the corresponding Hall voltage. Our results may help to explore antiferromagnetic skyrmions by electrical means in real materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate topological Hall effects in a metallic antiferromagnetic (AFM) thin film and/or at the interface of an AFM insulator–normal metal bilayer with a single skyrmion in the diffusive regime. To determine the spin- and charge Hall currents, we employed a Boltzmann kinetic equation with both spin-dependent and spin-flip scatterings. The interaction between conduction electrons and static skyrmions is included in the Boltzmann equation via the corresponding emergent magnetic field arising from the skyrmion texture. We compute intrinsic and extrinsic contributions to the topological spin Hall effect and spin accumulation, induced by an AFM skyrmion. We show that although the spin Hall current vanishes rapidly outside the skyrmion, the spin accumulation can be finite at the edges far from the skyrmion, provided the spin diffusion length is longer than the skyrmion radius. In addition, We show that in the presence of a spin-dependent relaxation time, the topological charge Hall effect is finite and we determine the corresponding Hall voltage. Our results may help to explore antiferromagnetic skyrmions by electrical means in real materials. |
| 16. | Anna Krzyżewska, Anna Dyrdał Bilinear magnetoresistance in 2DEG with isotropic cubic Rashba spin–orbit interaction Journal of Magnetism and Magnetic Materials, 589 , pp. 171615, 2024. @article{Krzyżewska2024, title = {Bilinear magnetoresistance in 2DEG with isotropic cubic Rashba spin–orbit interaction}, author = {Anna Krzyżewska and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323012659?via%3Dihub}, doi = {10.1016/j.jmmm.2023.171615}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = {171615}, abstract = {Bilinear magnetoresistance has been studied theoretically in 2D systems with isotropic cubic form of Rashba spin–orbit interaction. We have derived the effective spin–orbital field due to current-induced spin polarization and discussed its contribution to the unidirectional system response. The analyzed model can be applied to the semiconductor quantum wells as well as 2DEG at the surfaces and interfaces of perovskite oxides.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bilinear magnetoresistance has been studied theoretically in 2D systems with isotropic cubic form of Rashba spin–orbit interaction. We have derived the effective spin–orbital field due to current-induced spin polarization and discussed its contribution to the unidirectional system response. The analyzed model can be applied to the semiconductor quantum wells as well as 2DEG at the surfaces and interfaces of perovskite oxides. |
| 15. | Mirali Jafari, Anna Dyrdał Journal of Magnetism and Magnetic Materials, 589 , pp. 171618, 2024. @article{Jafari2024, title = {Effect of strain on the electronic and magnetic properties of bilayer T-phase VS2 : A first-principles study}, author = {Mirali Jafari and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323012684?via%3Dihub}, doi = {10.1016/j.jmmm.2023.171618}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = {171618}, abstract = {Using the Density Functional Theory (DFT) calculations, we determined the electronic and magnetic properties of a T-phase VS2 bilayer as a function of tensile and compressive strain. First, we determine the ground state structural parameters and then the band structure, magnetic anisotropy, exchange parameters, and Curie temperature. Variation of these parameters with the strain is carefully analyzed and described. The easy-plane anisotropy, which is rather small in the absence of strain, becomes remarkably enhanced by tensile strain and reduced almost to zero by compressive strain. We also show that the exchange parameters and the Curie temperature are remarkably reduced for the compressive strains below roughly −4%. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Using the Density Functional Theory (DFT) calculations, we determined the electronic and magnetic properties of a T-phase VS2 bilayer as a function of tensile and compressive strain. First, we determine the ground state structural parameters and then the band structure, magnetic anisotropy, exchange parameters, and Curie temperature. Variation of these parameters with the strain is carefully analyzed and described. The easy-plane anisotropy, which is rather small in the absence of strain, becomes remarkably enhanced by tensile strain and reduced almost to zero by compressive strain. We also show that the exchange parameters and the Curie temperature are remarkably reduced for the compressive strains below roughly −4%. |
2023 |
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| 14. | Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Journal of Magnetism and Magnetic Materials, 588 , pp. 171463, 2023. @article{Rudzinski2023, title = {Spin waves in monolayers of transition-metal dichalcogenides with Dzyaloshinskii - Moriya interaction}, author = {Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1016/j.jmmm.2023.171463}, doi = {10.1016/j.jmmm.2023.171463}, year = {2023}, date = {2023-12-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {588}, pages = {171463}, abstract = {Dzyaloshinski–Moriya interaction, known also as the antisymmetric exchange coupling, leads to a variety of interesting spin phenomena, like spin canting, skyrmion formation, nonreciprocal spin wave propagation, and others. In this paper we analyze spin waves in monolayers of two-dimensional van–der–Waals materials, such as Vanadium–based dichalcogenides, VX2 (X=S, Se, Te) and other materials of similar symmetry. The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dzyaloshinski–Moriya interaction, known also as the antisymmetric exchange coupling, leads to a variety of interesting spin phenomena, like spin canting, skyrmion formation, nonreciprocal spin wave propagation, and others. In this paper we analyze spin waves in monolayers of two-dimensional van–der–Waals materials, such as Vanadium–based dichalcogenides, VX2 (X=S, Se, Te) and other materials of similar symmetry. The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation. |
| 13. | Mirali Jafari, Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Electronic and magnetic properties of 2D vanadium-based transition metal dichalcogenides Scientific Reports, 13 , pp. 20947, 2023. @article{Jafari2023, title = {Electronic and magnetic properties of 2D vanadium-based transition metal dichalcogenides}, author = {Mirali Jafari and Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1038/s41598-023-48141-1}, doi = {10.1038/s41598-023-48141-1}, year = {2023}, date = {2023-11-28}, journal = {Scientific Reports}, volume = {13}, pages = {20947}, abstract = {In this paper, electronic and magnetic properties of monolayers and bilayers of Vanadium-based transition metal dichalcogenides VX2 (X = S, Se, Te) in the H phase are investigated theoretically using methods based on DFT calculations as well as analytical methods based on effective spin Hamiltonians. The band structure has been computed for all systems, and then the results have been used to determine exchange parameters and magnetic anisotropy constants. These parameters are subsequently used for the determination of the Curie temperatures, hysteresis curves, and energy of spin-wave excitations. In the latter case, we compare analytical results based on effective spin Hamiltonian with those determined numerically by Quantum ATK software and find a good agreement. The determined Curie temperature for VTe2 monolayers and bilayers is below the room temperature (especially that for bilayers), while for the other two materials, i.e. for VS2 and VSe2, it is above the room temperature, in agreement with available experimental data.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this paper, electronic and magnetic properties of monolayers and bilayers of Vanadium-based transition metal dichalcogenides VX2 (X = S, Se, Te) in the H phase are investigated theoretically using methods based on DFT calculations as well as analytical methods based on effective spin Hamiltonians. The band structure has been computed for all systems, and then the results have been used to determine exchange parameters and magnetic anisotropy constants. These parameters are subsequently used for the determination of the Curie temperatures, hysteresis curves, and energy of spin-wave excitations. In the latter case, we compare analytical results based on effective spin Hamiltonian with those determined numerically by Quantum ATK software and find a good agreement. The determined Curie temperature for VTe2 monolayers and bilayers is below the room temperature (especially that for bilayers), while for the other two materials, i.e. for VS2 and VSe2, it is above the room temperature, in agreement with available experimental data. |
| 12. | Anna Dyrdał, Alireza Qaiumzadeh, Arne Brataas, Józef Barnaś Magnon-plasmon hybridization mediated by spin-orbit interaction in magnetic materials Physical Review B, 108 (4), pp. 045414, 2023. @article{Dyrdał2023, title = {Magnon-plasmon hybridization mediated by spin-orbit interaction in magnetic materials}, author = {Anna Dyrdał and Alireza Qaiumzadeh and Arne Brataas and Józef Barnaś}, url = {https://doi.org/10.1103/PhysRevB.108.045414}, doi = {10.1103/PhysRevB.108.045414}, year = {2023}, date = {2023-07-21}, journal = {Physical Review B}, volume = {108}, number = {4}, pages = {045414}, abstract = {We propose a mechanism for magnon-plasmon coupling and hybridization in ferromagnetic (FM) and antiferromagnetic (AFM) systems. The electric field associated with plasmon oscillations creates a nonequilibrium spin density via the inverse spin galvanic effect. This plasmon-induced spin density couples to magnons by an exchange interaction. The strength of magnon-plasmon coupling depends on the magnetoelectric susceptibility of the system and the wavevector at which the level repulsion has happened. This wavevector may be tuned by an applied magnetic field. In AFM systems, the degeneracy of two chiral magnons is broken in the presence of a magnetic field, and we find two separate hybrid modes for left-handed and right-handed AFM magnons. Furthermore, we show that magnon-plasmon coupling in AFM systems is enhanced because of strong intrasublattice spin dynamics. We argue that the recently discovered two-dimensional magnetic systems are ideal platforms to investigate proposed magnon-plasmon hybrid modes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a mechanism for magnon-plasmon coupling and hybridization in ferromagnetic (FM) and antiferromagnetic (AFM) systems. The electric field associated with plasmon oscillations creates a nonequilibrium spin density via the inverse spin galvanic effect. This plasmon-induced spin density couples to magnons by an exchange interaction. The strength of magnon-plasmon coupling depends on the magnetoelectric susceptibility of the system and the wavevector at which the level repulsion has happened. This wavevector may be tuned by an applied magnetic field. In AFM systems, the degeneracy of two chiral magnons is broken in the presence of a magnetic field, and we find two separate hybrid modes for left-handed and right-handed AFM magnons. Furthermore, we show that magnon-plasmon coupling in AFM systems is enhanced because of strong intrasublattice spin dynamics. We argue that the recently discovered two-dimensional magnetic systems are ideal platforms to investigate proposed magnon-plasmon hybrid modes. |
| 11. | Ali Ebrahimian, Anna Dyrdał, Alireza Qaiumzadeh Scientific Reports, 13 , pp. 5336, 2023. @article{Ebrahimian2023, title = {Control of magnetic states and spin interactions in bilayer CrCl3 with strain and electric fields: an ab initio study}, author = {Ali Ebrahimian and Anna Dyrdał and Alireza Qaiumzadeh}, url = {https://doi.org/10.1038/s41598-023-32598-1}, doi = {10.1038/s41598-023-32598-1}, year = {2023}, date = {2023-04-01}, journal = {Scientific Reports}, volume = {13}, pages = {5336}, abstract = {Using ab initio density functional theory, we demonstrated the possibility of controlling the magnetic ground-state properties of bilayer CrCl3 by means of mechanical strains and electric fields. In principle, we investigated the influence of these two fields on parameters describing the spin Hamiltonian of the system. The obtained results show that biaxial strains change the magnetic ground state between ferromagnetic and antiferromagnetic phases. The mechanical strain also affects the direction and amplitude of the magnetic anisotropy energy (MAE). Importantly, the direction and amplitude of the Dzyaloshinskii–Moriya vectors are also highly tunable under external strain and electric fields. The competition between nearest-neighbor exchange interactions, MAE, and Dzyaloshinskii–Moriya interactions can lead to the stabilization of various exotic spin textures and novel magnetic excitations. The high tunability of magnetic properties by external fields makes bilayer CrCl3 a promising candidate for application in the emerging field of two-dimensional quantum spintronics and magnonics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Using ab initio density functional theory, we demonstrated the possibility of controlling the magnetic ground-state properties of bilayer CrCl3 by means of mechanical strains and electric fields. In principle, we investigated the influence of these two fields on parameters describing the spin Hamiltonian of the system. The obtained results show that biaxial strains change the magnetic ground state between ferromagnetic and antiferromagnetic phases. The mechanical strain also affects the direction and amplitude of the magnetic anisotropy energy (MAE). Importantly, the direction and amplitude of the Dzyaloshinskii–Moriya vectors are also highly tunable under external strain and electric fields. The competition between nearest-neighbor exchange interactions, MAE, and Dzyaloshinskii–Moriya interactions can lead to the stabilization of various exotic spin textures and novel magnetic excitations. The high tunability of magnetic properties by external fields makes bilayer CrCl3 a promising candidate for application in the emerging field of two-dimensional quantum spintronics and magnonics. |
2022 |
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| 10. | X.-G. Wang, L. Chotorlishvili, G. Tatara, Anna Dyrdał, Guang-hua Guo, V. K. Dugaev, Józef Barnaś, S.S.P. Parkin, A. Ernst Skyrmion lattice hosted in synthetic antiferromagnets and helix modes Phys. Rev. B, 106 , pp. 104424, 2022. @article{Wang2022b, title = {Skyrmion lattice hosted in synthetic antiferromagnets and helix modes}, author = {X.-G. Wang and L. Chotorlishvili and G. Tatara and Anna Dyrdał and Guang-hua Guo and V. K. Dugaev and Józef Barnaś and S.S.P. Parkin and A. Ernst}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.104424}, doi = {10.1103/PhysRevB.106.104424}, year = {2022}, date = {2022-09-20}, journal = {Phys. Rev. B}, volume = {106}, pages = {104424}, abstract = {Thin ferromagnetic films can possess unconventional magnetic properties, opening a new road for using them in spintronic technologies. In the present work exploiting three different methods, we comprehensively analyze phason excitations of a skyrmion lattice in synthetic antiferromagnets. To analyze phason excitations of the skyrmion lattice, we have constructed an analytical model based on three coupled helices and found a linear gapless mode. Micromagnetic simulations also support this result. Moreover, a similar result has been achieved within the rigid skyrmion lattice model based on the coupled Thiele's equations, when the coupling between skyrmions in different layers of the synthetic antiferromagnetic is comparable to or larger than the intralayer coupling. In addition, we also consider the orbital angular momentum and spin pumping current associated with phason excitations. Due to the gapless excitations in the case of skyrmion lattice, the pumping current is nonzero for the arbitrary frequency of pumping microwaves. In the case of individual skyrmions, no current is pumped when microwave frequency is inside the gap of the spectrum of individual skyrmions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Thin ferromagnetic films can possess unconventional magnetic properties, opening a new road for using them in spintronic technologies. In the present work exploiting three different methods, we comprehensively analyze phason excitations of a skyrmion lattice in synthetic antiferromagnets. To analyze phason excitations of the skyrmion lattice, we have constructed an analytical model based on three coupled helices and found a linear gapless mode. Micromagnetic simulations also support this result. Moreover, a similar result has been achieved within the rigid skyrmion lattice model based on the coupled Thiele's equations, when the coupling between skyrmions in different layers of the synthetic antiferromagnetic is comparable to or larger than the intralayer coupling. In addition, we also consider the orbital angular momentum and spin pumping current associated with phason excitations. Due to the gapless excitations in the case of skyrmion lattice, the pumping current is nonzero for the arbitrary frequency of pumping microwaves. In the case of individual skyrmions, no current is pumped when microwave frequency is inside the gap of the spectrum of individual skyrmions. |
| 9. | X.-G. Wang, Guang-hua Guo, Anna Dyrdał, Józef Barnaś, V. K. Dugaev, S. S. P. Parkin, A. Ernst, L. Chotorlishvili Skyrmion Echo in a System of Interacting Skyrmions Phys. Rev. Lett., 129 , pp. 126101, 2022. @article{Wang2022, title = {Skyrmion Echo in a System of Interacting Skyrmions}, author = {X.-G. Wang and Guang-hua Guo and Anna Dyrdał and Józef Barnaś and V. K. Dugaev and S. S. P. Parkin and A. Ernst and L. Chotorlishvili}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.126101}, doi = {10.1103/PhysRevLett.129.126101}, year = {2022}, date = {2022-09-14}, journal = {Phys. Rev. Lett.}, volume = {129}, pages = {126101}, abstract = {We consider helical rotation of skyrmions confined in the potentials formed by nanodisks. Based on numerical and analytical calculations we propose the skyrmion echo phenomenon. The physical mechanism of the skyrmion echo formation is also proposed. Because of the distortion of the lattice, impurities, or pinning effect, confined skyrmions experience slightly different local fields, which leads to dephasing of the initial signal. The interaction between skyrmions also can contribute to the dephasing process. However, switching the magnetization direction in the nanodiscs (e.g., by spin transfer torque) also switches the helical rotation of the skyrmions from clockwise to anticlockwise (or vice versa), and this restores the initial signal (which is the essence of skyrmion echo).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We consider helical rotation of skyrmions confined in the potentials formed by nanodisks. Based on numerical and analytical calculations we propose the skyrmion echo phenomenon. The physical mechanism of the skyrmion echo formation is also proposed. Because of the distortion of the lattice, impurities, or pinning effect, confined skyrmions experience slightly different local fields, which leads to dephasing of the initial signal. The interaction between skyrmions also can contribute to the dephasing process. However, switching the magnetization direction in the nanodiscs (e.g., by spin transfer torque) also switches the helical rotation of the skyrmions from clockwise to anticlockwise (or vice versa), and this restores the initial signal (which is the essence of skyrmion echo). |
| 8. | L. Chotorlishvili, Xi-guang Wang, Anna Dyrdał, Guang-hua Guo, Vitalii K. Dugaev, Józef Barnaś, J. Berakdar Rectification of the spin Seebeck current in noncollinear antiferromagnets Phys. Rev. B, 106 (1), pp. 014417, 2022, ISSN: 2469-9969. @article{Chotorlishvili2022, title = {Rectification of the spin Seebeck current in noncollinear antiferromagnets}, author = {L. Chotorlishvili and Xi-guang Wang and Anna Dyrdał and Guang-hua Guo and Vitalii K. Dugaev and Józef Barnaś and J. Berakdar}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.014417}, doi = {10.1103/PhysRevB.106.014417}, issn = {2469-9969}, year = {2022}, date = {2022-07-25}, journal = {Phys. Rev. B}, volume = {106}, number = {1}, pages = {014417}, abstract = {In the absence of an external magnetic field and a spin-polarized charge current, an antiferromagnetic system supports two degenerate magnon modes. An applied thermal bias activates the magnetic dynamics, leading to a magnon flow from the hot to the cold edge (magnonic spin Seebeck current). Both degenerate bands contribute to the magnon current but the orientations of the magnetic moments underlying the magnons are opposite in different bands. Therefore, while the magnon current is nonzero, the net spin current is zero. To obtain a nonzero net spin current, one needs to apply either a magnetic field or a spin-polarized charge current that lifts the bands' degeneracy. Here, attaching a thermal contact to one edge of a helical nanowire, we study three different magnonic spin currents: (i) the exchange, and (ii) Dzyaloshinskii–Moriya spin currents flowing along the helical nanowire, and (iii) magnonic spin current pumped into the adjacent normal-metal layer. We find that the combination of Dzyaloshinskii–Moriya interaction and external magnetic field substantially enhances the spin current compared to the current generated solely through a magnetic field. Due to nonreciprocal magnons and magnon dichroism effect, the Dzyaloshinskii–Moriya and exchange spin currents show left-right propagation asymmetry, with 20% of current rectification. The spin pumping current shows a slight asymmetry only in the case of a strong Dzyaloshinskii–Moriya interaction. The observed effects are explained in terms of the magnon dispersion relations and the magnon Doppler effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In the absence of an external magnetic field and a spin-polarized charge current, an antiferromagnetic system supports two degenerate magnon modes. An applied thermal bias activates the magnetic dynamics, leading to a magnon flow from the hot to the cold edge (magnonic spin Seebeck current). Both degenerate bands contribute to the magnon current but the orientations of the magnetic moments underlying the magnons are opposite in different bands. Therefore, while the magnon current is nonzero, the net spin current is zero. To obtain a nonzero net spin current, one needs to apply either a magnetic field or a spin-polarized charge current that lifts the bands' degeneracy. Here, attaching a thermal contact to one edge of a helical nanowire, we study three different magnonic spin currents: (i) the exchange, and (ii) Dzyaloshinskii–Moriya spin currents flowing along the helical nanowire, and (iii) magnonic spin current pumped into the adjacent normal-metal layer. We find that the combination of Dzyaloshinskii–Moriya interaction and external magnetic field substantially enhances the spin current compared to the current generated solely through a magnetic field. Due to nonreciprocal magnons and magnon dichroism effect, the Dzyaloshinskii–Moriya and exchange spin currents show left-right propagation asymmetry, with 20% of current rectification. The spin pumping current shows a slight asymmetry only in the case of a strong Dzyaloshinskii–Moriya interaction. The observed effects are explained in terms of the magnon dispersion relations and the magnon Doppler effect. |
| 7. | Mir Ali Jafari, A. A. Kordbacheh, Anna Dyrdał J. Magn. Magn. Mater., 554 , pp. 169260, 2022, ISSN: 0304-8853. @article{Jafari2022b, title = {Electronic and magnetic properties of silicene monolayer under bi-axial mechanical strain: First principles study}, author = {Mir Ali Jafari and A. A. Kordbacheh and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322002116?via%3Dihub}, doi = {10.1016/j.jmmm.2022.169260}, issn = {0304-8853}, year = {2022}, date = {2022-07-15}, journal = {J. Magn. Magn. Mater.}, volume = {554}, pages = {169260}, abstract = {Mechanical control of electronic and magnetic properties of 2D Van-der-Waals heterostructures gives new possibilities for further development of spintronics and information-related technologies. Using the density functional theory, we investigate the structural, electronic and magnetic properties of silicene monolayer with substituted Chromium atoms and under a small biaxial strain (-6% < e < 8%). Our results indicate that the Cr-doped silicene nanosheets without strain have magnetic metallic, half-metallic or semiconducting properties depending on the type of substitution. We also show that the magnetic moments associated with the monomer and vertical dimer substitutions change very weakly with strain. However, the magnetic moment associated with the horizontal dimer substitution decreases when either compressive or tensile strain is applied to the system. Additionally, we show that the largest semiconductor band-gap is approximately 0.13 eV under zero strain for the vertical Cr-doped silicene. Finally, biaxial compressive strain leads to irregular changes in the magnetic moment for Cr vertical dimer substitution.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Mechanical control of electronic and magnetic properties of 2D Van-der-Waals heterostructures gives new possibilities for further development of spintronics and information-related technologies. Using the density functional theory, we investigate the structural, electronic and magnetic properties of silicene monolayer with substituted Chromium atoms and under a small biaxial strain (-6% < e < 8%). Our results indicate that the Cr-doped silicene nanosheets without strain have magnetic metallic, half-metallic or semiconducting properties depending on the type of substitution. We also show that the magnetic moments associated with the monomer and vertical dimer substitutions change very weakly with strain. However, the magnetic moment associated with the horizontal dimer substitution decreases when either compressive or tensile strain is applied to the system. Additionally, we show that the largest semiconductor band-gap is approximately 0.13 eV under zero strain for the vertical Cr-doped silicene. Finally, biaxial compressive strain leads to irregular changes in the magnetic moment for Cr vertical dimer substitution. |
| 6. | Amir N. Zarezad, Anna Dyrdał Bilinear magnetoresistance in topological insulators: Role of magnetic disorder J. Magn. Magn. Mater., 552 , pp. 169167, 2022, ISSN: 0304-8853. @article{Zarezad2022, title = {Bilinear magnetoresistance in topological insulators: Role of magnetic disorder}, author = {Amir N. Zarezad and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322001329?via%3Dihub}, doi = {10.1016/j.jmmm.2022.169167}, issn = {0304-8853}, year = {2022}, date = {2022-06-15}, journal = {J. Magn. Magn. Mater.}, volume = {552}, pages = {169167}, abstract = {Bilinear magnetoresistance is a nonlinear transport phenomenon that scales linearly with the electric and magnetic fields, and appears in nonmagnetic systems with strong spin–orbit coupling, such as topological insulators (TIs). Using the semiclassical Boltzmann theory and generalized relaxation time approximation, we consider in detail the bilinear magnetoresistance in an effective model describing surface states of three-dimensional topological insulators. We show that the presence of magnetic impurities remarkably modifies the BMR signal. In general, scattering on magnetic impurities reduces magnitude of BMR. Apart from this, an additional modulation of the angular dependence of BMR appears when the spin-dependent component of the impurity potential dominates the scalar one.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bilinear magnetoresistance is a nonlinear transport phenomenon that scales linearly with the electric and magnetic fields, and appears in nonmagnetic systems with strong spin–orbit coupling, such as topological insulators (TIs). Using the semiclassical Boltzmann theory and generalized relaxation time approximation, we consider in detail the bilinear magnetoresistance in an effective model describing surface states of three-dimensional topological insulators. We show that the presence of magnetic impurities remarkably modifies the BMR signal. In general, scattering on magnetic impurities reduces magnitude of BMR. Apart from this, an additional modulation of the angular dependence of BMR appears when the spin-dependent component of the impurity potential dominates the scalar one. |
| 5. | Mir Ali Jafari, Anna Dyrdał Molecules, 27 (7), pp. 2228, 2022, ISSN: 1420-3049. @article{Jafari2022c, title = {First Principle Study on Electronic and Transport Properties of Finite-Length Nanoribbons and Nanodiscs for Selected Two-Dimensional Materials}, author = {Mir Ali Jafari and Anna Dyrdał}, url = {https://www.mdpi.com/1420-3049/27/7/2228}, doi = {10.3390/molecules27072228}, issn = {1420-3049}, year = {2022}, date = {2022-03-29}, journal = {Molecules}, volume = {27}, number = {7}, pages = {2228}, abstract = {Using the density functional theory, we calculate electronic states of various nanoribbons and nanodiscs formed from selected two-dimensional materials, such as graphene, silicene, and hexagonal boron nitride. The main objective of the analysis is a search for zero-energy states in such systems, which is an important issue as their presence indicates certain topological properties associated with chirality. The analysis is also supported by calculating transport properties.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Using the density functional theory, we calculate electronic states of various nanoribbons and nanodiscs formed from selected two-dimensional materials, such as graphene, silicene, and hexagonal boron nitride. The main objective of the analysis is a search for zero-energy states in such systems, which is an important issue as their presence indicates certain topological properties associated with chirality. The analysis is also supported by calculating transport properties. |
| 4. | Mir Ali Jafari, Małgorzata Wawrzyniak-Adamczewska, Stefan Stagraczyński, Anna Dyrdał, Józef Barnaś Spin valve effect in two-dimensional VSe2 system J. Magn. Magn. Mater., 548 , pp. 168921, 2022, ISSN: 0304-8853. @article{Jafari2022, title = {Spin valve effect in two-dimensional VSe2 system}, author = {Mir Ali Jafari and Małgorzata Wawrzyniak-Adamczewska and Stefan Stagraczyński and Anna Dyrdał and Józef Barnaś}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321011215?via%3Dihub}, doi = {10.1016/j.jmmm.2021.168921}, issn = {0304-8853}, year = {2022}, date = {2022-03-15}, journal = {J. Magn. Magn. Mater.}, volume = {548}, pages = {168921}, abstract = {Vanadium based dichalcogenides, VSe2, are two-dimensional materials in which magnetic Vanadium atoms are arranged in a hexagonal lattice and are coupled ferromagnetically within the plane. However, adjacent atomic planes are coupled antiferromagnetically. This provides new and interesting opportunities for application in spintronics and data storage and processing technologies. A spin valve magnetoresistance may be achieved when magnetic moments of both atomic planes are driven to parallel alignment by an external magnetic field. The resistance change associated with the transition from antiparallel to parallel configuration is qualitatively similar to that observed in artificially layered metallic magnetic structures. Detailed electronic structure of VSe2 was obtained from DFT calculations. Then, the ballistic spin-valve magnetoresistance was determined within the Landauer formalism. In addition, we also analyze thermal and thermoelectric properties. Both phases of VSe2, denoted as H and T, are considered.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vanadium based dichalcogenides, VSe2, are two-dimensional materials in which magnetic Vanadium atoms are arranged in a hexagonal lattice and are coupled ferromagnetically within the plane. However, adjacent atomic planes are coupled antiferromagnetically. This provides new and interesting opportunities for application in spintronics and data storage and processing technologies. A spin valve magnetoresistance may be achieved when magnetic moments of both atomic planes are driven to parallel alignment by an external magnetic field. The resistance change associated with the transition from antiparallel to parallel configuration is qualitatively similar to that observed in artificially layered metallic magnetic structures. Detailed electronic structure of VSe2 was obtained from DFT calculations. Then, the ballistic spin-valve magnetoresistance was determined within the Landauer formalism. In addition, we also analyze thermal and thermoelectric properties. Both phases of VSe2, denoted as H and T, are considered. |
| 3. | Kateryna Boboshko, Anna Dyrdał, Józef Barnaś Journal of Magnetism and Magnetic Materials, 545 , pp. 168698, 2022. @article{Boboshko2022, title = {Bilinear magnetoresistance in topological insulators: The role of spin–orbit scattering on impurities}, author = {Kateryna Boboshko and Anna Dyrdał and Józef Barnaś}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009318}, doi = {10.1016/j.jmmm.2021.168698}, year = {2022}, date = {2022-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {545}, pages = {168698}, abstract = {Bilinear magnetoresistance (BMR) is a new kind of magnetoresistance, that scales linearly with electric and magnetic fields. This magnetoresistance occurs in systems with strong spin–orbit interaction. Additionally, this interaction also leads to quadratic magnetoresistance (QMR). We consider theoretically BMR and QMR in surface states of 3D topological insulators, and propose a new mechanism that leads to these effects. This mechanism is based on scattering on spin–orbit impurities. Accordingly, we assume the minimal model of surface electronic states in a single independent surface of a TI, and calculate both BMR and QMR induced as an interplay of current-induced spin polarization (or equivalently effective spin–orbit field) and spin–orbit scattering on impurities. We present detailed characteristics of both BMR and QMR, and compare our results with those obtained for TIs with spin-momentum locking inhomogeneities and hexagonal warping of the Dirac cones.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bilinear magnetoresistance (BMR) is a new kind of magnetoresistance, that scales linearly with electric and magnetic fields. This magnetoresistance occurs in systems with strong spin–orbit interaction. Additionally, this interaction also leads to quadratic magnetoresistance (QMR). We consider theoretically BMR and QMR in surface states of 3D topological insulators, and propose a new mechanism that leads to these effects. This mechanism is based on scattering on spin–orbit impurities. Accordingly, we assume the minimal model of surface electronic states in a single independent surface of a TI, and calculate both BMR and QMR induced as an interplay of current-induced spin polarization (or equivalently effective spin–orbit field) and spin–orbit scattering on impurities. We present detailed characteristics of both BMR and QMR, and compare our results with those obtained for TIs with spin-momentum locking inhomogeneities and hexagonal warping of the Dirac cones. |
| 2. | Anna Krzyżewska, Anna Dyrdał Physica E, 135 , pp. 114961, 2022, ISSN: 1386-9477. @article{physicaE_2021.114961, title = {Non-equilibrium spin polarization in magnetic two-dimensional electron gas with k-linear and k-cubed Dresselhaus spin–orbit interaction}, author = {Anna Krzyżewska and Anna Dyrdał}, url = {https://doi.org/10.1016/j.physe.2021.114961}, doi = {10.1016/j.physe.2021.114961}, issn = {1386-9477}, year = {2022}, date = {2022-01-01}, journal = {Physica E}, volume = {135}, pages = {114961}, publisher = {North-Holland}, abstract = {The current-induced spin polarization (CISP) of charge carriers is one of the main mechanisms of spin-to-charge interconversion effects that can be used in new spintronics devices. Here, CISP is studied theoreticallyin symmetric quantum wells growing in [001] crystallographic direction, where both𝑘-linear and𝑘-cubedDresselhaus spin–orbit interactions are present. The exchange interaction responsible for perpendicular to planenet magnetization is also taken into account. The main focus is on the influence of cubic Dresselhaus termon CISP and the interplay between spin–orbit interaction (SOI) and the exchange field. The analytical andnumerical results are derived within the linear response theory and Matsubara Green’s function formalism.Apart from detailed numerical results, we also provide some analytical expressions that may be usefulfor interpretation of experimental results and for characterization of quantum wells with Dresselhaus SOI.Analytical expressions for the relevant Berry curvature are also derived, and it is shown that the Berrycurvature in magnetic 2DEG with cubic Dresselhaus interaction oscillates in the𝑘-space, while its averagedvalue is reduced. We also analyze the temperature behavior of CISP and calculate the low-temperature spinpolarizability due to heat current.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The current-induced spin polarization (CISP) of charge carriers is one of the main mechanisms of spin-to-charge interconversion effects that can be used in new spintronics devices. Here, CISP is studied theoreticallyin symmetric quantum wells growing in [001] crystallographic direction, where both𝑘-linear and𝑘-cubedDresselhaus spin–orbit interactions are present. The exchange interaction responsible for perpendicular to planenet magnetization is also taken into account. The main focus is on the influence of cubic Dresselhaus termon CISP and the interplay between spin–orbit interaction (SOI) and the exchange field. The analytical andnumerical results are derived within the linear response theory and Matsubara Green’s function formalism.Apart from detailed numerical results, we also provide some analytical expressions that may be usefulfor interpretation of experimental results and for characterization of quantum wells with Dresselhaus SOI.Analytical expressions for the relevant Berry curvature are also derived, and it is shown that the Berrycurvature in magnetic 2DEG with cubic Dresselhaus interaction oscillates in the𝑘-space, while its averagedvalue is reduced. We also analyze the temperature behavior of CISP and calculate the low-temperature spinpolarizability due to heat current. |
2021 |
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| 1. | Michał Inglot, Vitalii K. Dugaev, Anna Dyrdał, Józef Barnaś Phys. Rev. B, 104 (21), pp. 214408, 2021, ISSN: 2469-9969. @article{Inglot2021, title = {Graphene with Rashba spin-orbit interaction and coupling to a magnetic layer: Electron states localized at the domain wall}, author = {Michał Inglot and Vitalii K. Dugaev and Anna Dyrdał and Józef Barnaś}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.104.214408}, doi = {10.1103/PhysRevB.104.214408}, issn = {2469-9969}, year = {2021}, date = {2021-12-06}, journal = {Phys. Rev. B}, volume = {104}, number = {21}, pages = {214408}, abstract = {Electron states localized at a magnetic domain wall in a graphene with Rashba spin-orbit interaction and coupled to a magnetic layer are studied theoretically. It is shown that two one-dimensional bands of edge modes propagating along the domain wall emerge in the energy gap for each Dirac point, and the modes associated with different Dirac points K and K′ are the same. The coefficients describing decay of the corresponding wave functions with distance from the domain wall contain generally real and imaginary terms. Numerical results on the local spin density and on the total spin expected in the edge states characterized by the wave number ky are presented and discussed. The Chern number for a single magnetic domain on graphene indicates that the system is in the quantum anomalous Hall phase, with two chiral modes at the edges. In turn, the number of modes localized at the domain wall is determined by the difference in Chern numbers on both sides of the wall. These numbers are equal to 2 and −2, respectively, so there are four modes localized at the domain wall.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electron states localized at a magnetic domain wall in a graphene with Rashba spin-orbit interaction and coupled to a magnetic layer are studied theoretically. It is shown that two one-dimensional bands of edge modes propagating along the domain wall emerge in the energy gap for each Dirac point, and the modes associated with different Dirac points K and K′ are the same. The coefficients describing decay of the corresponding wave functions with distance from the domain wall contain generally real and imaginary terms. Numerical results on the local spin density and on the total spin expected in the edge states characterized by the wave number ky are presented and discussed. The Chern number for a single magnetic domain on graphene indicates that the system is in the quantum anomalous Hall phase, with two chiral modes at the edges. In turn, the number of modes localized at the domain wall is determined by the difference in Chern numbers on both sides of the wall. These numbers are equal to 2 and −2, respectively, so there are four modes localized at the domain wall. |