Direct observation of the exchange anisotropy in the helimagnetic insulator Cu${}_2$OSeO${}_3$

Abstract

The helical magnetic structures of cubic chiral systems are well-explained by the competition among Heisenberg exchange, Dzyaloshinskii-Moriya interaction, cubic anisotropy, and anisotropic exchange interaction (AEI). Recently, the role of the latter has been argued theoretically to be crucial for the low-temperature phase diagram of the cubic chiral magnet Cu${}_2$OSeO${}_3$, which features tilted conical and disordered skyrmion states for a specific orientation of the applied magnetic field (${\mu }_0\vec{\mathrm{H}}\parallel [001]$). In this study, we exploit transmission resonant x-ray scattering ($t-$REXS) in vector magnetic fields to directly quantify the strength of the AEI in Cu${}_2$OSeO${}_3$, and measure its temperature dependence. We find that the AEI continuously increases below 50\,K, resulting in a conical spiral pitch variation of $10\%$ in the (001) plane. Our results contribute to establishing the interaction space that supports tilted cone and low-temperature skyrmion state formation, facilitating the goals for both a quantitative description and eventual design of the diverse spiral states existing amongst chiral magnets.

References in corpus (8)

• Advances in the Physics of Magnetic Skyrmions and Perspective for Technology
• Electric field-induced Skyrmion distortion and giant lattice rotation in the magnetoelectric insulator Cu2OSeO3
• Observation of two independent skyrmion phases in a chiral magnetic material
• Nanometric skyrmion lattice from anisotropic exchange interactions in a centrosymmetric host
• Metastable skyrmion lattices governed by magnetic disorder and anisotropy in $\beta$-Mn-type chiral magnets
• Microwave spectroscopy of the low-temperature skyrmion state in Cu2OSeO3
• Field and anisotropy driven transformations of spin spirals in cubic skyrmion hosts
• Experimental Evidence of a change of Exchange Anisotropy Sign with Temperature in Zn-Substituted Cu2OSeO3

Cited by in corpus (6)

• Fluctuation-driven topological Hall effect in room-temperature itinerant helimagnet Fe3Ga4
• Imaging magnetic spiral phases, skyrmion clusters, and skyrmion displacements at the surface of bulk Cu${}_2$OSeO${}_3$
• Observation of magnetic skyrmion lattice in Cr${}_{0.82}$Mn${}_{0.18}$Ge by small-angle neutron scattering
• Observation of distorted tilted conical phase at the surface of a bulk chiral magnet with resonant elastic x-ray scattering
• Magnetic field-induced chiral soliton lattice in the bulk magnetoelectric helimagnet Cu${}_2$OSeO${}_3$
• Helical spin dynamics in Cu${}_2$OSeO${}_3$ as measured with small-angle neutron scattering