Magnetism and critical behavior of double perovskite RE 2CoMnO6 (RE = La and Eu) compounds

The magnetic properties and critical behavior near the Curie temperature T_C in the double perovskite RE₂CoMnO₆ (RE = La and Eu) were systematically investigated via the modified Arrott plots (MAP), the Kouvel-Fisher plot (K-F), and the critical isotherm analysis (CI). The reliable value of critical parameters (β, δ, and γ) obtained from K-F plot are to be 0.4704, 0.9978, and 3.12 with T_C of 210.8 K for La₂CoMnO₆, and to be 0.6065, 0.9237, and 2.52 with T_C of 130.3 K for Eu₂CoMnO₆, respectively. Moreover, the reliability of critical parameters of two samples was further verified by different methods including the Widom scaling relation and the magnetic equation. The obtained values of critical parameters are all close to the value of the mean-field theoretical model which manifested the presence of the long-range FM order for RE₂CoMnO₆ (RE = La and Eu) compounds.