Field-induced reorientation of helimagnetic order in Cu${}_2$OSeO${}_3$ probed by magnetic force microscopy

Abstract

Cu${}_2$OSeO${}_3$ is an insulating skyrmion-host material with a magnetoelectric coupling giving rise to an electric polarization with a characteristic dependence on the magnetic field $\vec{H}$. We report magnetic force microscopy imaging of the helical real-space spin structure on the surface of a bulk single crystal of Cu${}_2$OSeO${}_3$. In the presence of a magnetic field, the helimagnetic order in general reorients and acquires a homogeneous component of the magnetization, resulting in a conical arrangement at larger fields. We investigate this reorientation process at a temperature of 10~K for fields close to the crystallographic $⟨110⟩$ direction that involves a phase transition at $H_{c1}$. Experimental evidence is presented for the formation of magnetic domains in real space as well as for the microscopic origin of relaxation events that accompany the reorientation process. In addition, the electric polarization is measured by means of Kelvin-probe force microscopy. We show that the characteristic field dependency of the electric polarization originates in this helimagnetic reorientation process. Our experimental results are well described by an effective Landau theory previously invoked for MnSi, that captures the competition between magnetocrystalline anisotropies and Zeeman energy.

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Cited by in corpus (7)

• Screw dislocations in cubic chiral magnets
• Critical Sample Aspect Ratio and Magnetic Field Dependence for Antiskyrmion Formation in Mn1.4PtSn Single-Crystals
• Tunable Cooperativity in Coupled Spin--Cavity Systems
• Chiral surface spin textures in Cu${}_2$OSeO${}_3$ unveiled by soft x-ray scattering in specular reflection geometry
• Imaging magnetic spiral phases, skyrmion clusters, and skyrmion displacements at the surface of bulk Cu${}_2$OSeO${}_3$
• Observation of distorted tilted conical phase at the surface of a bulk chiral magnet with resonant elastic x-ray scattering
• Evidence of spin reorientation transition below 150 K from magnetic force microscopy in a ferromagnetic BiFeO${}_3$ thin film