Spin-Orbit Torques in Two-Dimensional Rashba Ferromagnets

TL;DR

This paper uses functional Keldysh theory to analyze spin-orbit torques in 2D Rashba ferromagnets, revealing conditions under which intrinsic anti-damping-like torque appears, with implications for magnetization control.

Contribution

It provides a microscopic calculation of Rashba spin-orbit torques in 2D ferromagnets, including vertex corrections, clarifying when intrinsic anti-damping-like torque exists.

Findings

Reactive, anti-damping-like torque is calculated microscopically.

Dissipative, field-like torque is also derived.

Intrinsic anti-damping torque vanishes unless scattering rates are spin-dependent.

Abstract

Magnetization dynamics in single-domain ferromagnets can be triggered by charge current if spin-orbit coupling is sufficiently strong. We apply functional Keldysh theory to investigate Rashba spin-orbit torques in metallic two-dimensional ferromagnets. A reactive, anti-damping-like spin-orbit torque as well as a dissipative, field-like torque are calculated microscopically, to the leading order in the spin-orbit interaction strength. By calculating the first vertex correction we show that the intrinsic anti-damping-like torque vanishes unless the scattering rates are spin-dependent.