Skyrmion and meron phases induced by spin-phonon coupling

Abstract

In chiral magnets, magnetic skyrmions are typically stabilized by the competition between exchange and Dzyaloshinskii-Moriya interactions under an external magnetic field, while the role of lattice degrees of freedom has received comparatively less attention. Here we study how spin-phonon (SP) coupling modifies magnetic interactions and the resulting spin textures in a two-dimensional skyrmion model in the square lattice. Using Monte Carlo simulations, we compare two simplified models describing the SP coupling: the Einstein site-phonon (ESP) and bond-phonon (BP) models. We find that ESP coupling stabilizes skyrmion crystals in field regimes that are topologically trivial in the uncoupled model and also induces additional textures, including meron-antimeron (M-aM) crystals and mixed skyrmion-bimeron (SkX-Bm) phases. Furthermore, for sufficiently strong phonon coupling, the conventional triple-$\textbf{q}$ hexagonal skyrmion lattice is distorted into a double-$\textbf{q}$ square skyrmion lattice. Overall, our results show that lattice effects provide a simple mechanism to tune topological magnetic phases.