Tilted Spirals and Low Temperature Skyrmions in Cu2OSeO3

TL;DR

This study investigates the stability and behavior of tilted spiral and skyrmion phases in Cu2OSeO3 at low temperatures, revealing temperature-dependent anisotropy effects that influence magnetic state stability.

Contribution

It provides a systematic analysis of low-temperature magnetic states in Cu2OSeO3, extending understanding of their temperature and field dependencies and their theoretical description.

Findings

Tilted spiral phase persists up to 35 K.

Strong cubic anisotropy stabilizes skyrmions at low temperatures.

Anisotropy constants show pronounced temperature dependence.

Abstract

The bulk helimagnet Cu2OSeO3 represents a unique example in the family of B20 cubic helimagnets exhibiting a tilted spiral and skyrmion phase at low temperatures when the magnetic field is applied along the easy <001> crystallographic direction. Here we present a systematic study of the stability and ordering of these low temperature magnetic states. We focus our attention on the temperature and field dependencies of the tilted spiral state that we observe persisting up to above T =35 K, i.e. up to higher temperatures than reported so far. We discuss these results in the frame of the phenomenological theory introduced by Dzyaloshinskii in an attempt to reach a quantitative description of the experimental findings. We find that the anisotropy constants, which are the drivers behind the observed behaviour, exhibit a pronounced temperature dependence. This explains the differences in the behaviour observed at high temperatures (above T = 18 K), where the cubic anisotropy is weak, and at low temperatures (below T = 18 K), where a strong cubic anisotropy induces an abrupt appearance of the tilted spirals out of the conical state and enhances the stability of skyrmions.