Direct observation of domain-wall configurations transformed by spin currents

TL;DR

This study directly visualizes how spin-polarized currents move and transform magnetic domain walls in FeNi wires, revealing a correlation between spin structure changes and velocity decay during current pulses.

Contribution

It provides the first direct imaging of domain-wall transformations induced by spin currents, linking spin structure changes to dynamic behavior in ferromagnetic wires.

Findings

Current pulses move domain walls in the direction of electron flow.

Domain walls transform from vortex to transverse configurations with pulse injections.

Wall velocity decays as a function of injected current pulses.

Abstract

Direct observations of current-induced domain-wall propagation by spin-polarized scanning electron microscopy are reported. Current pulses move head-to-head as well as tail-to-tail walls in sub-micrometer Fe_{20}Ni_{80} wires in the direction of the electron flow, and a decay of the wall velocity with the number of injected current pulses is observed. High-resolution images of the domain walls reveal that the wall spin structure is transformed from a vortex to a transverse configuration with subsequent pulse injections. The change in spin structure is directly correlated with the decay of the velocity.