The Experts below are selected from a list of 14799 Experts worldwide ranked by ideXlab platform
Konstantin Y Guslienko - One of the best experts on this subject based on the ideXlab platform.
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steady one dimensional Domain wall motion in biaxial ferromagnets mapping of the landau lifshitz equation to the sine gordon equation
Physical Review B, 2020Co-Authors: R Ramaeiroa, R M Otxoa, P E Roy, Konstantin Y GuslienkoAbstract:Motivated by the difference between the dynamics of magnetization textures in ferromagnets and antiferromagnets, the Landau-Lifshitz equation of motion is explored. A typical one-dimensional Domain wall in a bulk ferromagnet with biaxial magnetic anisotropy is considered. In the framework of Walker-type solutions of steady-state Ferromagnetic Domain wall motion, the reduction of the nonlinear Landau-Lifshitz equation to a Lorentz-invariant sine-Gordon equation typical for antiferromagnets is formally possible for velocities lower than a critical velocity of the topological soliton. The velocity dependence of the Domain wall energy and the Domain wall width are expressed in the relativistic-like form in the limit of large ratio of the easy-plane/easy-axis anisotropy constants. It is shown that the mapping of the Landau-Lifshitz equation of motion to the sine-Gordon equation can be performed only by going beyond the steady-motion Walker-type solutions.
Kyung Jin Lee - One of the best experts on this subject based on the ideXlab platform.
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numerical computation of spin transfer torques for antiFerromagnetic Domain walls
Physical Review B, 2020Co-Authors: Hyeon Jong Park, Hyunwoo Lee, Yunboo Jeong, Kyoungwhan Kim, Kyung Jin LeeAbstract:We numerically compute current-induced spin-transfer torques for antiFerromagnetic Domain walls, based on a linear response theory in a tight-binding model. We find that, unlike for Ferromagnetic Domain-wall motion, the contribution of adiabatic spin torque to antiFerromagnetic Domain-wall motion is negligible, consistent with previous theories. As a result, the nonadiabatic spin-transfer torque is a main driving torque for antiFerromagnetic Domain-wall motion. Moreover, the nonadiabatic spin-transfer torque for narrower antiFerromagnetic Domain walls increases more rapidly than that for Ferromagnetic Domain walls, which is attributed to the enhanced spin mistracking process for antiFerromagnetic Domain walls.
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AntiFerromagnetic Domain Wall Motion Driven by Spin-Orbit Torques.
Physical review letters, 2016Co-Authors: Takayuki Shiino, Byongguk Park, Paul M. Haney, Seo Won Lee, Kyung Jin LeeAbstract:We theoretically investigate the dynamics of antiFerromagnetic Domain walls driven by spin-orbit torques in antiferromagnet-heavy-metal bilayers. We show that spin-orbit torques drive antiFerromagnetic Domain walls much faster than Ferromagnetic Domain walls. As the Domain wall velocity approaches the maximum spin-wave group velocity, the Domain wall undergoes Lorentz contraction and emits spin waves in the terahertz frequency range. The interplay between spin-orbit torques and the relativistic dynamics of antiFerromagnetic Domain walls leads to the efficient manipulation of antiFerromagnetic spin textures and paves the way for the generation of high frequency signals from antiferromagnets.
Jinbo Yang - One of the best experts on this subject based on the ideXlab platform.
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enhancement of exchange bias in Ferromagnetic antiFerromagnetic core shell nanoparticles through Ferromagnetic Domain wall formation
Physical Review B, 2018Co-Authors: Rui Wu, Shilei Ding, Guang Tian, Jinbo YangAbstract:The spin configuration in the Ferromagnetic part during the magnetization reversal plays a crucial role in the exchange bias effect. Through Monte Carlo simulation, the exchange bias effect in Ferromagnetic-antiFerromagnetic core-shell nanoparticles is investigated. Magnetization reversals in the Ferromagnetic core were controlled between the coherent rotation and the Domain wall motion by modulating Ferromagnetic Domain wall width with parameters of uniaxial anisotropy constant and exchange coupling strength. An anomalous monotonic dependence of exchange bias on the uniaxial anisotropy constant is found in systems with small exchange coupling, showing an obvious violation of classic Meiklejohn-Bean model, while Domain walls are found to form close to the interface and propagate in the Ferromagnetic core with larger uniaxial anisotropy in both branches of the hysteresis. The asymmetric magnetization reversal with the formation of a spherical Domain wall dramatically reduces the coercive field in the ascending branch, leading to the enhancement of the exchange bias. The results provide another degree of freedom to optimize the magnetic properties of magnetic nanoparticles for applications.
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enhancement of exchange bias in Ferromagnetic antiFerromagnetic core shell nanoparticles through Ferromagnetic Domain wall formation
Physical Review B, 2018Co-Authors: Shilei Ding, Guang Tian, Youfang Lai, Jinbo YangAbstract:The spin configuration in the Ferromagnetic part during the magnetization reversal plays a crucial role in the exchange bias effect. Through Monte Carlo simulation, the exchange bias effect in Ferromagnetic-antiFerromagnetic core-shell nanoparticles is investigated. Magnetization reversals in the Ferromagnetic core were controlled between the coherent rotation and the Domain wall motion by modulating the Ferromagnetic Domain wall width with parameters of uniaxial anisotropy constant and exchange coupling strength. An anomalous monotonic dependence of exchange bias on the uniaxial anisotropy constant is found in systems with small exchange coupling, showing an obvious violation of classic Meiklejohn-Bean model, while Domain walls are found to form close to the interface and propagate in the Ferromagnetic core with larger uniaxial anisotropy in both branches of the hysteresis. The asymmetric magnetization reversal with the formation of a spherical Domain wall dramatically reduces the coercive field in the ascending branch, leading to the enhancement of the exchange bias. The results provide another degree of freedom to optimize the magnetic properties of magnetic nanoparticles for applications.
R Ramaeiroa - One of the best experts on this subject based on the ideXlab platform.
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steady one dimensional Domain wall motion in biaxial ferromagnets mapping of the landau lifshitz equation to the sine gordon equation
Physical Review B, 2020Co-Authors: R Ramaeiroa, R M Otxoa, P E Roy, Konstantin Y GuslienkoAbstract:Motivated by the difference between the dynamics of magnetization textures in ferromagnets and antiferromagnets, the Landau-Lifshitz equation of motion is explored. A typical one-dimensional Domain wall in a bulk ferromagnet with biaxial magnetic anisotropy is considered. In the framework of Walker-type solutions of steady-state Ferromagnetic Domain wall motion, the reduction of the nonlinear Landau-Lifshitz equation to a Lorentz-invariant sine-Gordon equation typical for antiferromagnets is formally possible for velocities lower than a critical velocity of the topological soliton. The velocity dependence of the Domain wall energy and the Domain wall width are expressed in the relativistic-like form in the limit of large ratio of the easy-plane/easy-axis anisotropy constants. It is shown that the mapping of the Landau-Lifshitz equation of motion to the sine-Gordon equation can be performed only by going beyond the steady-motion Walker-type solutions.
Sayeef Salahuddin - One of the best experts on this subject based on the ideXlab platform.
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deterministic Domain wall motion orthogonal to current flow due to spin orbit torque
Scientific Reports, 2015Co-Authors: Debanjan Bhowmik, Mark E Nowakowski, Long You, Oukjae Lee, David Keating, Mark Wong, Jeffrey Bokor, Sayeef SalahuddinAbstract:Spin-polarized electrons can move a Ferromagnetic Domain wall through the transfer of spin angular momentum when current flows in a magnetic nanowire. Such current induced control of a Domain wall is of significant interest due to its potential application for low power ultra high-density data storage. In previous reports, it has been observed that the motion of the Domain wall always happens parallel to the current flow – either in the same or opposite direction depending on the specific nature of the interaction. In contrast, here we demonstrate deterministic control of a Ferromagnetic Domain wall orthogonal to current flow by exploiting the spin orbit torque in a perpendicularly polarized Ta/CoFeB/MgO heterostructure in presence of an in-plane magnetic field. Reversing the polarity of either the current flow or the in-plane field is found to reverse the direction of the Domain wall motion. Notably, such orthogonal motion with respect to current flow is not possible from traditional spin transfer torque driven Domain wall propagation even in presence of an external magnetic field. Therefore the Domain wall motion happens purely due to spin orbit torque. These results represent a completely new degree of freedom in current induced control of a Ferromagnetic Domain wall.