Asymmetric Antibimerons: Statics and Dynamics

Abstract

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 has yet to be observed experimentally. We show that AABs can be stabilized by an anisotropic interfacial Dzyaloshinskii-Moriya interaction, characteristic of materials with $D_{2d}$ symmetry. Using energy considerations, we explain the origin of its asymmetric shape, composed of an antivortex and a crescent-shaped vortex with opposite core polarizations. Furthermore, we demonstrate that AABs of opposite topological charge can coexist within the same ferromagnetic film, in contrast to skyrmions in out-of-plane magnetized systems. Employing micromagnetic simulations and an analytical approach based on an extension of Thiele's equation to a system of two elliptic merons comprising the AAB, we are able to describe the current-driven dynamics of AABs. In particular, we show that AAB collisions enable controlled manipulation of the system's topological charge. Our findings shed light on fundamental understanding of asymmetric topological magnetic solitons and provide a roadmap for their experimental observation in in-plane magnetized ferromagnets.

7 pages, 4 figures