Magnetic anisotropy and reversal in epitaxial Fe/MgO(001) films revisited

TL;DR

This study revisits magnetization reversal mechanisms in epitaxial Fe/MgO(001) films, revealing a new two-step domain wall nucleation process that better explains experimental observations than previous models.

Contribution

It introduces a revised understanding of magnetization reversal involving two successive domain wall nucleations, challenging the previously accepted 180° domain wall nucleation model.

Findings

A new reversal mechanism with two domain wall nucleations explains the switching fields.

The mechanism applies across various field orientations.

Results improve interpretation of magnetization reversal in epitaxial thin films.

Abstract

We investigate the magnetization reversal in Fe/MgO(001) films with fourfold in-plane magnetic anisotropy and an additional uniaxial anisotropy whose orientation and strength are tuned using different growth geometries and post growth treatments. The previously adopted mechanism of 180^{o} domain wall nucleation clearly fails to explain the observed 180^{o} magnetization reversal. A new reversal mechanism with two successive domain wall nucleations consistently predicts the switching fields for all field orientations. Our results are relevant for a correct interpretation of magnetization reversal in many other epitaxial metallic and semiconducting thin films.