Field-induced reorientation of helimagnetic order in Cu 2 OSeO 3 probed by magnetic force microscopy

Cu${}_{2}$OSeO${}_{3}$ is an insulating skyrmion host material with a magnetoelectric coupling giving rise to electric polarization. Using magnetic force microscopy on the surface of a bulk single crystal, the authors study here the helical real-space spin structure and its reorientation under applied magnetic field. Using Kelvin probe force microscopy, they also measure the field dependency of the electric polarization originating in this reorientation process. An effective Landau theory capturing the competition between magnetocrystalline anisotropies and Zeeman energy is in excellent agreement with the experimental results.