Long wavelength helimagnetic order and skyrmion lattice phase in Cu2OSeO3

TL;DR

This paper reveals a long-wavelength helimagnetic order and skyrmion lattice phase in the insulator Cu2OSeO3, showing similarities to binary helimagnets and suggesting spin fluctuations influence its magneto-dielectric properties.

Contribution

It reports the discovery of a helimagnetic superstructure and skyrmion phase in Cu2OSeO3, expanding understanding of magnetic phases in ferrimagnetic insulators.

Findings

Identification of a skyrmion lattice phase in Cu2OSeO3

Temperature dependence of specific heat indicates critical spin fluctuations

Magnetic phase diagram resembles that of binary helimagnets

Abstract

We report a long-wavelength helimagnetic superstructure in bulk samples of the ferrimagnetic insulator Cu2OSeO3. The magnetic phase diagram associated with the helimagnetic modulation inferred from small angle neutron scattering and magnetisation measurements includes a skyrmion lattice phase and is strongly reminiscent of MnSi, FeGe and Fe1-xCoxSi, i.e., binary isostructural siblings of Cu2OSeO3 that order helimagnetically. The temperature dependence of the specific heat of Cu2OSeO3 is characteristic of nearly critical spin fluctuations at the helimagnetic transition. This provides putative evidence for effective spin currents as the origin of enhancements of the magneto-dielectric response instead of atomic displacements considered so far.