Magnetic domain walls displacement : automotion vs. spin-transfer torque

TL;DR

This paper experimentally demonstrates automotion of magnetic domain walls in nanostrips, showing that structural relaxation can cause significant displacement independent of spin transfer torque, with implications for magnetic device control.

Contribution

It provides the first experimental evidence of automotion in domain walls, highlighting its importance alongside spin transfer torque in magnetic nanostrip dynamics.

Findings

Automotion causes domain wall displacement exceeding spin transfer torque effects.

Transforming metastable walls results in large, measurable displacements.

Analytical and numerical models explain the automotion phenomenon.

Abstract

The magnetization dynamics equation predicts that a domain wall that changes structure should undergo a displacement by itself - automotion - due to the relaxation of the linear momentum that is associated with the wall structure. We experimentally demonstrate this effect in soft nanostrips,transforming under spin transfer torque a metastable asymmetric transverse wall into a vortex wall. Displacements more than three times as large as under spin transfer torque only are measured for 1~ns pulses. The results are explained by analytical and numerical micromagnetics. Their relevance to domain wall motion under spin transfer torque is emphasized.