Critical behavior and reversible magnetocaloric effect in multiferroic MnCr2O4

Magnetocaloric effect (MCE) in multiferroic cubic spinel MnCr2O4 (space group Fd3¯m, no. 227, cF56), has been investigated using dc magnetization studies. The values of maximum magnetic entropy change (ΔSMmax) and the adiabatic temperature change (ΔTad) are ∼5.3 J kg−1 K−1 and ∼2 K, respectively, at ∼42.8 K for the magnetic field change of 50 kOe. The dc magnetization data near the transition temperature were analyzed by the modified Arrott plots, the Kouvel-Fisher method, log M vs log H, and the scaling analysis. Critical exponents β = 0.3932 ± 0.0287, γ = 1.0256 ± 0.0239, and δ = 3.55 ± 0.26 are obtained around the critical temperature ∼42.88 K. The critical exponents are in excellent agreement with the single scaling equation of state M(H,∊)=∊0.3932±0.0287 f±(H/∊((0.3932±0.0287)+(1.0256±0.0239))); with f+ for T > 42.88 K, f- for T < 42.88 K, and ∊ = (T − 42.88)/42.88. At T = 42.88 K, the exponent δ relates the magnetization with applied filed by M=H1/(3.55±0.26). Scaling analysis shows that calculated critical exponents as well as critical temperature are intrinsic to the system. Theoretically, the value of β is close to 3D Heisenberg model, while values of γ and δ are close to those of the mean field model. So the values of critical exponents indicate that the critical behavior of MnCr2O4 cannot be described within the framework of existing universality classes and probably belong to a separate class.