Critical behavior of spinel MnV2O4 investigated by dc-magnetization

Critical behavior of spinel vanadate oxide MnV2O4 has been investigated by the dc-magnetization study. Critical exponents beta = 0.349 +/- 0.009, gamma=0.909 +/- 0.002, and delta=2.913 +/- 0.003 are obtained in the critical asymptotic region around the critical temperature T-C. With these critical exponents, experimental M-T-H curves collapse onto two independent universal branches below and above T-C, respectively, indicating the reliability of the obtained results. The critical exponents gamma and delta are close to the mean-field model with long-range interaction, while the value of beta deviates to the 3D-Heisenberg model with short-range coupling. It is suggested that a long-range ferromagnetic coupling exists for Mn2+-Mn2+ interaction, which competes with the short-range interaction of V3+ sublattice. Moreover, the precursor phenomenon of the orbital ordering could be observed from the critical behavior, which indicates orbital fluctuation in MnV2O4. (C) 2014 AIP Publishing LLC.