An investigation of reentrant spin-glass behavior, magnetocaloric effect and critical behavior of MnCr2O4

Abstract

The spin-glass (SG) behavior, magnetocaloric effect, and critical behavior of MnCr2O4 were investigated using dc/ac magnetic measurements. The strong magnetic anisotropy is observed from the dc magnetizations. The peaks of ac susceptibility display dependence on the frequency and magnetic field. Meanwhile, magnetic relaxation measurements show a slow decay of the remanent magnetization with time. These findings consistently demonstrate the coexistence of the SG component and long-range ferrimagnetic (FIM) order in MnCr2O4. The SG at low temperature is not conventional but has a reentrant character. Importantly, the reentrant SG (RSG) behavior in MnCr2O4 originates from the freezing and fluctuation of the short-range spiral order at low temperatures. On the other hand, the magnetocaloric effect (MCE) in spinel compounds MnCr2O4 was reported in this study. According to the isotherms measurements, the magnetic entropy change |ΔSM|=6.1 J kg−1 K−1 was calculated under applied field H = 50 kOe. A comprehensive study of the critical behavior of MnCr2O4 near the paramagnetic (PM) to FIM transition, might be helpful in understanding the interesting magnetic interaction of MnCr2O4. Besides, the critical exponents of MnCr2O4 was obtained [β = 0.488 and γ = 0.918 for MAP, β = 0.473 and γ = 0.909 for KF] by the different theoretical models. Interestingly, it is found that the critical phenomena of MnCr2O4 are close to the mean-field model.