Temperature-driven transition from skyrmion to bubble crystals in centrosymmetric itinerant magnets

TL;DR

This study reveals a temperature-induced transition from skyrmion to bubble crystal states in centrosymmetric itinerant magnets, highlighting the role of thermal effects and magnetic interactions in topological spin textures.

Contribution

It demonstrates the existence of a finite-temperature transition between skyrmion and bubble crystals in a centrosymmetric system using large-scale simulations and effective spin models.

Findings

Finite-temperature topological phase transition identified.

Transition driven by temperature change in a classical Kondo lattice model.

Synergy between multiple-spin interactions and magnetic anisotropy is crucial.

Abstract

Interplay between itinerant electrons and localized spins in itinerant magnets gives rise to a variety of noncoplanar multiple-$Q$ spin textures, such as the skyrmion, hedgehog, meron, and vortex. We elucidate that another type of multiple-$Q$ state consisting of collinear sinusoidal waves, a magnetic bubble crystal, appears at finite temperatures in a centrosymmetric itinerant electron system. The results are obtained for the classical Kondo lattice model with easy-axis single-ion anisotropy on a triangular lattice by a large-scale numerical simulation. We find that a finite-temperature topological phase transition between the skyrmion crystal and the bubble crystal occurs by changing the temperature. We obtain the minimal key ingredients for inducing the finite-temperature transition by analyzing an effective spin model where it is shown that the synergy between the multiple-spin interaction and magnetic anisotropy plays a significant role.