Critical behavior at paramagnetic to ferrimagnetic phase transition in A-site ordered perovskite CaCu3Cr2Nb2O12

A new perovskite-type oxide, CaCu3Cr2Nb2O12, has been synthesized at 10 GPa and 1100 °C. The compound crystallizes in space group Im3¯ with 1:3 ordered Ca and Cu cations at the A sites and disordered Cr and Nb cations at the octahedral B sites. CaCu3Cr2Nb2O12 exhibits a paramagnetic–ferrimagnetic transition at around 192.3 K and the Arrott plots manifest this transition is a second-order transition. We investigate the critical behavior of CaCu3Cr2Nb2O12 using the modified Arrott plots, Kouvel–Fisher plot, and the scale theory. The estimated critical exponents β, γ and δ, which yield β = 0.465 ± 0.006, γ = 1.312 ± 0.019 and δ = 3.833 ± 0.019 with TC = 197 K, fall within the predicted values from the mean-field model and three-dimensional Heisenberg model. The renormalization group analysis suggests that the exchange interaction decays as J(r) ∼ r−4.871, indicating the magnetic interactions may be long-range coupling in CaCu3Cr2Nb2O12.