Magnetization dynamics driven by angle-dependent spin-orbit spin transfer torque

TL;DR

This paper provides a theoretical analysis of how angle-dependent spin-orbit torque influences magnetization switching and domain wall motion, offering analytic formulas and insights for experimental design.

Contribution

It introduces analytic expressions for switching current and domain wall velocity considering angle-dependent spin-orbit torque, advancing understanding of magnetization dynamics.

Findings

Spin-orbit torque increases with the polar angle enhances switching efficiency.

Analytic expressions agree with numerical simulations.

Guidelines for designing experiments based on spin-orbit torque.

Abstract

Spin-orbit spin transfer torque allows an efficient control of magnetization by an in-plane current. Recent experiments found that the spin-orbit torque has strong dependence on the magnetization angle [Garello et al., Nature Nanotechnol. 8, 587 (2013); Qiu et al., Sci. Rep. 4, 4491 (2014)]. We theoretically investigate magnetization switching and domain wall motion in a perpendicularly magnetized layer, induced by angle-dependent spin-orbit torque. We obtain analytic expressions of the switching current and domain wall velocity, in agreement with numerical results. Based on the expressions, we find that the spin-orbit torque increasing with the polar angle of magnetization is beneficial for both switching and domain wall motion. Our result will serve as a guideline to design and interpret switching and domain wall experiments based on spin-orbit torque.