Magnetic skyrmions are nanoscale vortices of spins that may provide a number of interesting device applications ranging from high-density, low-power data storage to stochastic and neuromorphic computing. To form a hexagonal lattice of skyrmions requires the presence of competing interactions, namely the Dzyaloshinskii-Moriya interaction (DMI) and exchange interactions found in inversions of anti-symmetric materials.
One example is Cu2OSeO3, which has been found to contain a number of incommensurate magnetic textures, including skyrmions, cones and helices, at a range of temperatures. In this study, published in Physical Review Research, researchers used small angle neutron scattering to study and quantify the magnetic interactions present in (Cu0.98Zn0.02)2OSeO3 to elucidate the formation mechanisms of these magnetic states.
The authors found that they were able to investigate the anisotropic exchange interaction using the 3D vector-field magnet at the Larmor beamline, by orienting the conical states in the material along different directions and investigating the variations in the periodicity. Interestingly, the interaction changes sign on decreasing temperature, but without inducing a reorientation of the zero-field magnetic helix. This insight into the behaviour of this material is crucial for understanding how to create and stabilise these complex magnetic textures.
Related publication: Experimental evidence of a change of exchange anisotropy sign with temperature in Zn-substituted Cu2OSeO3, Phys. Rev. Research, 3, 043149 DOI: 10.1103/PhysRevResearch.3.043149