Universality Class Transition Across the Helimagnetic Ordering in Te-doped Cu2OSeO3

Cu ₂ OSeO ₃ 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 behavior remains elusive. In this work, Cu ₂ OSe _{1 −  x} Te _x O ₃ with (0 ≤  x  ≤ 0.1) is synthesized 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 polarized phase transition. Furthermore, the stability region of the skyrmion lattice also expands. We present a universality class analysis on the materials using the Heat-map Modified Iteration Method to evaluate the critical behavior and show that the Heisenberg to Ising transition is robust to chemical doping. Additionally, we demonstrate that the change to both critical temperature and critical field to be due to decreases in the strengths of the Dzyaloshinskii-Moriya and Symmetric Exchange Interactions upon doping.