Magnetic domain walls in nanostrips of single-crystalline $\mathrm{Fe}_4\mathrm{N}(001)$ thin films with fourfold in-plane magnetic anisotropy

TL;DR

This study explores the unique properties of magnetic domain walls in epitaxial Fe4N(001) nanostrips with fourfold in-plane anisotropy, revealing how their structure and behavior depend on strip orientation and magnetic field application.

Contribution

It provides new insights into the domain wall structures and transformations in Fe4N(001) nanostrips with fourfold anisotropy, combining experimental and simulation approaches.

Findings

Domain walls exhibit specific structures depending on strip orientation.

Partial flux-closure domains form below a critical width.

Transformation from transverse to vortex walls occurs under magnetic fields.

Abstract

We investigated head-to-head domain walls in nanostrips of epitaxial $\mathrm{Fe}_4\mathrm{N}(001)$ thin films, displaying a fourfold magnetic anisotropy. Magnetic force microscopy and micromagnetic simulations show that the domain walls have specific properties, compared to soft magnetic materials. In particular, strips aligned along a hard axis of magnetization are wrapped by partial flux-closure concertina domains below a critical width, while progressively transforming to zigzag walls for wider strips. Transverse walls are favored upon initial application of a magnetic field transverse to the strip, while transformation to a vortex walls is favored upon motion under a longitudinal magnetic field. In all cases the magnetization texture of such fourfold anisotropy domain walls exhibits narrow micro-domain walls, which may give rise to peculiar spin-transfer features.