Head-to-head domain walls in one-dimensional nanostructures: an extended phase diagram ranging from strips to cylindrical wires

TL;DR

This paper presents an extended phase diagram for magnetic domain walls in one-dimensional nanostructures, unifying flat strips and cylindrical wires through symmetry, phase-transition analysis, and micromagnetic simulations.

Contribution

It introduces a comprehensive phase diagram covering various geometries and classifies domain walls based on topology, supported by analytical and numerical methods.

Findings

Unified phase diagram for domain walls in 1D structures

Classification into transverse/vortex and Bloch-point types

Scaling laws for iso-energy lines

Abstract

So far magnetic domain walls in one-dimensional structures have been described theoretically only in the cases of flat strips, or cylindrical structures with a compact cross-section, either square or disk. Here we describe an extended phase diagram unifying the two pictures, extensively covering the (width,thickness) space. It is derived on the basis of symmetry and phase-transition arguments, and micromagnetic simulations. A simple classification of all domain walls in two varieties is proposed on the basis of their topology: either with a combined transverse/vortex character, or of the Bloch-point type. The exact arrangement of magnetization within each variety results mostly from the need to decrease dipolar energy, giving rise to asymmetric and curling structures. Numerical evaluators are introduced to quantify curling, and scaling laws are derived analytically for some of the iso-energy lines of the phase diagram.