Critical behavior and magnetocaloric effect in the multiferroic double perovskite Lu2NiMnO6

A systematic investigation on the structure, magnetism, magnetocaloric effect, and critical behaviors of multiferroic Lu2NiMnO6 synthesized by sol-gel method are reported. This compound crystallizes in a monoclinic structure with the space group P21/n. Upon decreasing temperature, a single magnetic transition from paramagnetic to ferromagnetic phase has been observed, around which considerable magnetic entropy changes can be obtained. Besides, evaluation of the critical exponents are performed using various techniques, like the modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis based on the magnetic data around magnetic transition temperature. The obtained critical exponent values are found to be coincided and comparable with those predicted by the mean-field model, which are also confirmed by the single scaling equation: m = f±(h), where m and h are the renormalized magnetization and field, respectively by observation of isotherm M(H) curves below and above the critical temperatures collapsing into two independent universal branches. The exponents determined in this study are in good agreement with those calculated from the renormalization group approach for a three-dimensional system coupled with the attractive long-range interactions between spins that decay as J(r)∼r−(3+σ) with σ = 1.325.