Antidamping spin-orbit torque driven by spin-flip reflection mechanism on the surface of a topological insulator: A time-dependent nonequilibrium Green function approach

Abstract

Motivated by recent experiments observing spin-orbit torque (SOT) acting on the magnetization $\vec{m}$ of a ferromagnetic (F) overlayer on the surface of a three-dimensional topological insulator (TI), we investigate the origin of the SOT and the magnetization dynamics in such systems. We predict that lateral F/TI bilayers of finite length, sandwiched between two normal metal leads, will generate a large antidamping-like SOT per very low charge current injected parallel to the interface. The large values of antidamping-like SOT are {\it spatially localized} around the transverse edges of the F overlayer. Our analysis is based on adiabatic expansion (to first order in $\partial \vec{m}/\partial t$) of time-dependent nonequilibrium Green functions (NEGFs), describing electrons pushed out of equilibrium both by the applied bias voltage and by the slow variation of a classical degree of freedom [such as $\vec{m}(t)$]. From it we extract formulas for spin torque and charge pumping, which show that they are reciprocal effects to each other, as well as Gilbert damping in the presence of SO coupling. The NEGF-based formula for SOT naturally splits into four components, determined by their behavior (even or odd) under the time and bias voltage reversal. Their complex angular dependence is delineated and employed within Landau-Lifshitz-Gilbert simulations of magnetization dynamics in order to demonstrate capability of the predicted SOT to efficiently switch $\vec{m}$ of a perpendicularly magnetized F overlayer.

11 pages, 6 figures

References in corpus (11)

• New Perspectives for Rashba Spin-Orbit Coupling
• Spin Transfer Torques
• Anomalous Bias Dependence of Spin Torque in Magnetic Tunnel Junctions
• Surface State Magnetization and Chiral Edge States on Topological Insulators
• Intraband and interband spin-orbit torques in non-centrosymmetric ferromagnets
• Spin-orbit torque driven chiral magnetization reversal in ultrathin nanostructures
• Angular dependence of spin-orbit spin transfer torques
• Microwave-driven ferromagnet--topological-insulator heterostructures: The prospect for giant spin battery effect and quantized charge pump devices
• Spin-Orbit Torques in Two-Dimensional Rashba Ferromagnets
• Nonequilibrium spin texture within a thin layer below the surface of current-carrying topological insulator Bi${}_2$Se${}_3$: A first-principles quantum transport study
• Topological Surface States Originated Spin-Orbit Torques in Bi2Se3

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