Head-to-Head Domain Wall Structures in Wide Permalloy Strips

TL;DR

This study uses micromagnetic simulations to explore various equilibrium domain wall structures in wide Permalloy strips, revealing new vortex configurations and metastable states across different geometries.

Contribution

The paper introduces a comprehensive phase diagram of domain wall structures in wide Permalloy strips, including previously unreported double and triple vortex walls.

Findings

Identification of new double and triple vortex domain walls.

Presence of multiple metastable states in wide and thick strips.

Robustness of results against damping and initial conditions.

Abstract

We analyze the equilibrium micromagnetic domain wall structures encountered in Permalloy strips of a wide range of thicknesses and widths, with strip widths up to several micrometers. By performing an extensive set of micromagnetic simulations, we show that the equilibrium phase diagram of the domain wall structures exhibits in addition to the previously found structures (symmetric and asymmetric transverse walls, vortex wall) also double vortex and triple vortex domain walls for large enough strip widths and thicknesses. Also several metastable domain wall structures are found for wide and/or thick strips. We discuss the details of the relaxation process from random magnetization initial states towards the stable domain wall structure, and show that our results are robust with respect to changes of e.g. the magnitude of the Gilbert damping constant and details of the initial conditions.