Anisotropy driven response of skyrmion lattice in MnSc$_2$S$_4$ to applied magnetic fields

TL;DR

This study combines theoretical simulations and experimental neutron diffraction to explore how magnetic anisotropy influences the stability and orientation of antiferromagnetic skyrmion lattices in MnSc2S4 under applied magnetic fields.

Contribution

It provides a detailed analysis of the anisotropy-driven response of skyrmion lattices, confirming the effective spin model predictions with experimental data and revealing the destabilization of skyrmions at certain conditions.

Findings

Skyrmion lattice aligns within symmetric planes inclined to the magnetic field.

Neutron diffraction confirms the model's predictions.

Skyrmions destabilize at low temperatures and moderate fields, transitioning to a conical phase.

Abstract

We theoretically and experimentally study the stability of the unconventional fractional antiferromagnetic skyrmion lattice (AF-SkL) in Mn$_2$S$_4$ spinel under magnetic fields applied along the $[$1-10$]$ crystal direction. By performing numerical Monte Carlo simulations for the minimal effective spin model that we proposed in Ref. [S. Gao, et al., Nature 586, 37-41 (2020)], we show that the skyrmion lattice is aligned within the equivalent and symmetric $[$1-11$]$ or $[$1-11$]$ planes, which are equally inclined to the applied magnetic field. We attribute this behavior to the magnetic anisotropy of the host material. Neutron single crystal diffraction presents a very good agreement with the predictions of the effective model. It reveals that the topological spin texture gets destabilized at low temperatures and moderate magnetic fields and is replaced by a conical phase for B// $[$1-10$]$. The present study elucidates the central role of the magnetic anisotropy in the stabilization of antiferromagnetic skyrmionic states.