Moving magnetic domain walls with sound alone

TL;DR

This paper demonstrates that surface acoustic waves can move magnetic domain walls without external magnetic fields or electric currents, revealing a new method for controlling magnetization in spintronic devices.

Contribution

It provides the first experimental and theoretical evidence that acoustic waves alone can induce magnetic domain wall motion, enabling field-free control of magnetization.

Findings

SAW induces magnetic domain wall motion in the direction of wave propagation

Maximum measured domain wall velocity was ~12 m/s

Simulations suggest velocities up to 100 m/s are possible

Abstract

Surface Acoustic Waves (SAW) have been used in spintronic applications to decrease the magnetic field or the electric current required to act on the magnetization. A common belief is that a SAW alone cannot achieve a directed magnetic switching in a device without an assisting magnetic field or electric current. In this work, we demonstrate magnetic domain wall motion driven solely by an acoustic wave. Using XMCD-PEEM, we show extensive evidence of SAW-induced and field-free magnetic domain wall motion (DW) in the direction of the wave propagation. Our micromagnetic simulations reveal a mechanism that allows the SAW to transfer linear momentum to the DW. Experimentally, the largest DW average velocity measured was ~12 m/s, although our simulations predict that velocities in the range of 100 m/s could be attained. This new mechanism opens the door to designing innovative spintronic devices where the magnetization can be controlled exclusively by an acoustic wave.