Asymmetric Antibimerons: Statics and Dynamics

TL;DR

This paper predicts and analyzes asymmetric antibimerons, a new type of topological spin texture in in-plane magnetized chiral ferromagnets, exploring their stability, shape, and current-driven dynamics through simulations and analytical methods.

Contribution

It introduces the concept of asymmetric antibimerons stabilized by anisotropic Dzyaloshinskii-Moriya interaction and studies their properties and dynamics, which are novel compared to existing topological textures.

Findings

AABs can be stabilized in $D_{2d}$ symmetry materials.

AABs exhibit asymmetric shapes with antivortex and crescent-shaped vortex.

The topological charge of AABs can be controlled via collisions.

Abstract

The nontrivial topological spin textures, such as magnetic skyrmions, are of great interest due to their potential use as information carriers in spintronic memory and logic. Here, we theoretically predict an asymmetric antibimeron (AAB) -- a topological texture in an in-plane magnetized chiral ferromagnet with $D_{2d}$ symmetry, which is yet to be observed experimentally. We show that it can be stabilized by an anisotropic interfacial Dzyaloshinskii-Moriya interaction found in materials with $D_{2d}$ symmetry. Using energy considerations, we explain its asymmetric shape formed of an antivortex and a crescent-shaped vortex of opposite core polarizations. Furthermore, we demonstrate that AABs of opposite topological charge can be stabilized within the same ferromagnetic film, unlike skyrmions in out-of-plane magnetized films. Employing micromagnetic simulations and analytical Thiele's equation approach, we also investigate current-driven dynamics of the AABs, in particular showing that the topological charge of the system can be controllably changed in AAB collisions. Our results shed light on fundamental understanding of asymmetric topological magnetic solitons and provide guidance for their experimental observation in in-plane magnetized ferromagnets.