Enhancement of Curie temperature and magnetoresistance in the perovskites La2/3Ca1/3Mn1-xSixO3

Structural, magnetic, and transport properties of perovskite La2/3Ca1/3Mn1-xSixO3 (x = 0, 0.025, 0.05) have been studied. The incorporation of Si decreases the overall resistivity, but obviously increases the Curie temperature (T-C), metal-insulator transition temperature (T-P), and the magnetoresistance ratio Mn (defined as [R(0) - R(H)]/R(0)) near room temperature. Comparing with La2/3Ca1/3MnO3, the T-C, T-P, and MR of the sample with x = 0.05 increase by 30, 45K, and 20%, respectively. Lattice effects may play a more important role than the magnetic dilution in the case of low Si substitution.