New magnetic phase of the chiral skyrmion material Cu2OSeO3

TL;DR

This paper reports a novel magnetic multi-domain state in Cu2OSeO3, deviating from the universal phase diagram of cubic chiral magnets, characterized by spiral wave vector rotation and associated magnetic fluctuations.

Contribution

The study uncovers a new multi-domain magnetic state in Cu2OSeO3, expanding understanding of magnetic phases in chiral skyrmion materials.

Findings

Discovery of a multi-domain state in Cu2OSeO3

Observation of spiral wave vector rotation near critical field

Identification of magnetic fluctuations and multiferroic properties

Abstract

The lack of inversion symmetry in the crystal lattice of magnetic materials gives rise to complex non-collinear spin orders through interactions of relativistic nature, resulting in interesting physical phenomena, such as emergent electromagnetism. Studies of cubic chiral magnets revealed a universal magnetic phase diagram, composed of helical spiral, conical spiral and skyrmion crystal phases. Here, we report a remarkable deviation from this universal behavior. By combining neutron diffraction with magnetization measurements we observe a new multi-domain state in Cu2OSeO3. Just below the upper critical field at which the conical spiral state disappears, the spiral wave vector rotates away from the magnetic field direction. This transition gives rise to large magnetic fluctuations. We clarify physical origin of the new state and discuss its multiferroic properties.