Multiple skyrmionic states and oblique spirals in bulk cubic helimagnets

Abstract

This chapter is mainly devoted to the distinctive properties of spiral and skyrmion states accounted by the cubic anisotropy in bulk cubic helimagnets such as MnSi and Cu2OSeO3. We start by systematizing the main features of the universal phase diagrams at the critical fields Hc1 and Hc2. We first discuss the influence of cubic anisotropy on the reversible, or irreversible, alignment of oblique spiral states into the conical phase at Hc1. We then address the phase transition between the conical and field-polarized state at Hc2, which may be of both first order and second order depending on the orientation of the applied magnetic field with respect to easy anisotropy axes. We show that the effect of cubic anisotropy is more subtle than assumed so far, as it may induce new elliptically distorted spiral states and phase transitions between them. Finally, we show how this distortion of the spiral states by cubic anisotropy opens up the way to skyrmion stabilization.