Critical behavior of Mo-doping La0.67Sr0.33Mn1-xMoxO3 perovskite system

摘要

Structure, magnetization, and specific heat have been investigated for the Mo-doping La0.67Sr0.33Mn1-x MoxO3 (x = 0, 0.01, 0.02, 0.03, 0.04, 0.06) perovskite system. The ferromagnetic to paramagnetic transition temperature T, is found to decrease from 369 K for x = 0 to 361 K for x = 0.06 with increasing Mo doping. According to a second-order phase transition model, the critical behavior near T-c are investigated systematically based on the specific heat data, and the critical exponents are determined to be alpha = 0.04-0.06, beta = 0.35-0.41, gamma = 1.13-1.25. The values of the critical exponents are found to keep almost same magnitude for La0.67Sr0.33Mn1-xMoxO3, system. It is noticed that the value of the critical exponent beta locates between the mean-field value (beta = 0.5) and the three-dimensional (3D) Ising model value (beta = 0.325), which suggests the coexistence of the short-range and long-range ferromagnetic orders around the critical temperature. The fundamental factors to dominate the magnitude of the critical exponent values for the perovskite-type manganese oxide systems have been discussed as well.