Nonperturbative approach to interfacial spin-orbit torques induced by Rashba effect

Abstract

Current-induced spin-orbit torque (SOT) in normal metal/ferromagnet (NM/FM) bilayers bears great promise for technological applications, but the microscopic origin of purely interfacial SOTs in ultra-thin systems is not yet fully understood. Here, we show that a linear response theory with a nonperturbative treatment of spin-dependent interactions and impurity scattering potential predicts damping-like SOTs that are strictly absent in perturbative approaches. The technique is applied to a two-dimensional Rashba-coupled ferromagnet (the paradigmatic model of a NM/FM interface), where higher-order scattering processes encoding skew scattering from nonmagnetic impurities allow for current-induced spin polarization with nonzero components along all spatial directions. This is in stark contrast to previous results of perturbative methods (neglecting skew scattering), which predict a coplanar spin-polarization locked perpendicular to the charge current as a result of conventional Rashba-Edelstein effect. Furthermore, the angular dependence of ensuing SOTs and their dependence upon the scattering potential strength is analysed numerically. Simple analytic expressions for the spin-density--charge-current response function, and related SOT efficiencies, are obtained in the weak scattering limit. We find that the extrinsic damping-like torques driven by impurity scattering reaches efficiencies of up to 7% of the field-like (Rashba-Edelstein) torque. Our microscopic theory shows that bulk phenomena, such as the spin Hall effect, are not a necessity in the generation of the damping-like SOTs of the type observed in experiments on ultra-thin systems.

arXiv comment9 Pages, 4 figures

References in corpus (32)

• Spin Transfer Torques
• Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems
• Spin Transfer Torque Generated by the Topological Insulator Bi_2Se_3
• Symmetry and magnitude of spin-orbit torques in ferromagnetic heterostructures
• Layer thickness dependence of the current induced effective field vector in Ta|CoFeB|MgO
• Spin torque building blocks
• Current induced torques and interfacial spin-orbit coupling: Semiclassical Modeling
• Ultrafast magnetization switching by spin-orbit torques
• Spin-orbit-torque magnetization switching of a three terminal perpendicular magnetic tunnel junction
• Theory of the anomalous Hall effect from the Kubo formula and the Dirac equation
• Spin Transport at Interfaces with Spin-Orbit Coupling: Phenomenology
• Diffusive spin dynamics in ferromagnetic thin films with a Rashba interaction
• Theory of Spin-Charge Coupled Transport in a Two-Dimensional Electron Gas with Rashba Spin-Orbit Interactions
• Diffuse transport and spin accumulation in a Rashba two-dimensional electron gas
• Magneto-Optical Detection of the Spin Hall Effect in Pt and W Thin Films
• Optimal charge-to-spin conversion in graphene on transition metal dichalcogenides
• Extrinsic spin Hall effect induced by resonant skew scattering in graphene
• First-principles theory of proximity spin-orbit torque on a two-dimensional magnet: Current-driven antiferromagnet-to-ferromagnet reversible transition in bilayer CrI${}_3$
• Microscopic theory of spin-orbit torques and skyrmion dynamics
• Diffusive and precessional spin dynamics in a two-dimensional electron gas with disorder: a gauge theory view
• Covariant conservation laws and the spin Hall effect in Dirac-Rashba systems
• Spin-orbit torque opposing the Oersted torque in ultrathin Co/Pt bilayers
• Microscopic Theory of Spin Relaxation Anisotropy in Graphene with Proximity-Induced Spin-Orbit Coupling
• Anomalous Hall effect in 2D Dirac materials
• Quantum Diagrammatic Theory of the Extrinsic Spin Hall Effect in Graphene
• Interfacial contributions to spin-orbit torque and magnetoresistance in ferromagnet/heavy-metal bilayers
• Semiclassical theory of spin-orbit torques in disordered multiband electron systems
• Skew-scattering-induced giant antidamping spin-orbit torques: Collinear and out-of-plane Edelstein effects at two-dimensional material/ferromagnet interfaces
• Microscopic linear response theory of spin relaxation and relativistic transport phenomena in graphene
• Rashba torque beyond the Boltzmann regime
• Spin-charge conversion in disordered two-dimensional electron gases lacking inversion symmetry
• Theory of spin-charge-coupled transport in proximitized graphene: An SO(5) algebraic approach

Cited by in corpus (4)

• Control of charge-spin interconversion in van der Waals heterostructures with chiral charge density waves
• Quantum Kinetic Theory of the Linear Response for Weakly Disordered Multiband Systems
• The Role of Self-Torques in Transition Metal Dichalcogenide/Ferromagnet Bilayers
• Reconciling Kubo and Keldysh Approaches to Fermi-Sea-Dependent Nonequilibrium Observables: Application to Spin Hall Current and Spin-Orbit Torque in Spintronics