Skyrmion stabilisation and critical behaviour in tellurium-doped Cu2OSeO3

Cu2OSeO3 is a chiral magnet with a rich phase diagram. The positions of the phase transitions are sensitive to chemical substitution; however, the exact mechanism by which dopants influence magnetic behaviour remains elusive. In this work, Cu2OSe1−xTexO3 with (0 ≤ x ≤ 0.1) is synthesised with the lattice expanding upon Te inclusion. Our SANS and magnetometry data indicate that doping lowers the paramagnetic to helical ordering temperature and the critical field required for the conical to field-polarised phase transition. We present a universality class analysis on the materials using the Heatmap Modified Iteration Method to evaluate the critical behaviour and show that the Heisenberg to Ising transition is robust to chemical doping. However, we demonstrate that the inclusion of Te decreases both the strengths of the Dzyaloshinskii-Moriya and Symmetric Exchange Interactions. This led to an expansion of the skyrmion region and decreased both the critical temperature and field. Cu2OSeO3 is a chiral magnet with a rich phase diagram, but how dopants affect its magnetism remains unclear. In Cu2OSe1-xTexO3, the critical behaviour is examined through the Heatmap-Modified Iteration Method, while neutron scattering and magnetometry reveal skyrmion region expansion and reduced critical temperature and field with doping.