Anisotropic skyrmion liquid phase

TL;DR

This study investigates how anisotropic skyrmion-skyrmion interactions affect the melting transition in two-dimensional magnetic skyrmion systems, revealing a shift from a two-step to a direct solid-liquid transition.

Contribution

It demonstrates that atomic lattice-induced anisotropy can alter the skyrmion melting process, enabling a direct transition without an intermediate hexatic phase.

Findings

Isotropic interactions lead to a solid-hexatic-liquid transition.

Anisotropic interactions cause a direct solid-liquid transition.

Orientational order persists up to 30 K in the liquid phase with anisotropy.

Abstract

The nature of the melting transition in two-dimensional systems of particles has attracted considerable research attention since the development of Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory. The hexatic phase proposed by this theory has been recently identified experimentally in ensembles of magnetic skyrmions, quasiparticles formed in a magnetically ordered crystal. Here, we use quasiparticle dynamical simulations to study how the anisotropy of the skyrmion-skyrmion interactions induced by the atomic lattice influences the melting transition. For isotropic interactions, we find a transition from a solid phase through a hexatic phase stable in a narrow temperature range to an isotropic liquid phase. However, if the interactions between skyrmions are forced to be anisotropic by the atomic lattice, then a direct solid-liquid transition can be observed with orientational order persisting up to temperatures of 30 K in the liquid phase.