Structure, magnetic, and thermal properties of Nd_(1-x)La_xCro_3 (0≤x≤1.0)

摘要

Perovskite-type Nd_(1-x)La_xCrO_3 (0≤x≤1.0) polycrystalline samples were synthesized using solid state reaction. Structural studies indicate that the lattice parameters, metal-oxygen bond lengths, and angles of Nd_(1-x)La_xCrO_3 strongly depend on the La content. Two magnetic transition temperatures, Cr~(3+) antiferromagnetic ordering temperature (T_n) and the spin reorientation phase transition temperature (T_(SRPT)), have been observed in the M-T curves. The increase in T_N and decrease in T_(SRPT) with increasing x value can be explained by the change in the magnetic interactions due to La doping. The heat capacity of Nd_(1-x)La_xCrO_3 measured from 2 to 300 K reveals that the lattice, electronic, and magnetic contributions to heat capacity can be well interpreted quantitatively using the Debye and Schottky models. The splitting energy of the Cr~(3+) 3dt)2g orbital and the Nd~(3+) ground state have been calculated by fitting to the Schottky anomaly at very low temperature. The Cr-Nd interaction is suppressed gradually by La doping, which is verified by the calculation of the mean-field interaction parameter. This doping dependence provides directed evidence of TM-RE magnetic interactions in perovskite compounds, in agreement with the proposed model.