Chirality Sensitive Domain Wall Motion in Spin-Orbit Coupled Ferromagnets

TL;DR

This paper analytically investigates how Rashba spin-orbit coupling affects the motion of domain walls in ferromagnets, revealing chirality-dependent behavior that can distinguish spin-orbit effects from non-adiabatic torques.

Contribution

It provides an exact analytical solution for domain wall velocity considering spin-orbit coupling, non-equilibrium spins, and damping, highlighting chirality sensitivity.

Findings

Domain wall velocity depends on chirality due to spin-orbit interaction.

Reentrant behavior of domain wall velocity observed with changing chirality.

Quantitative estimates of domain wall speed based on experimental parameters.

Abstract

Using the Lagrangian formalism, we solve analytically the equations of motion for current-induced domain-wall dynamics in a ferromagnet with Rashba spin-orbit coupling. An exact solution for the domain wall velocity is provided, including the effect of non-equilibrium conduction electron spin-density, Gilbert damping, and the Rashba interaction parameter. We demonstrate explicitly that the influence of spin-orbit interaction can be qualitatively different from the role of non-adiabatic spin-torque in the sense that the former is sensitive to the chirality of the domain wall whereas the latter is not: the domain wall velocity shows a reentrant behavior upon changing the chirality of the domain wall. This could be used to experimentally distinguish between the spin-orbit and non-adiabatic contribution to the wall speed. A quantitative estimate for the attainable domain wall velocity is given, based on an experimentally relevant set of parameters for the system.