摘要
Structural,magnetic,and transport properties of perovskite La_(2/3)Ca_(1/_3)Mn_(1-x)Si_(x)O_(3)(x=0,0.025,0.05)have been studied.The incorporation of Si decreases the overall resistivity,but obviously increases the Curie temperature(TC),metal-insulator transition temperature(TP),and the magnetoresistance ratio MR(defined as[R(0)-R(H)]/R(0))near room temperature.Comparing with La_(2/3)Ca_(1/_3)MnO_(3)the TC,TP,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.
基金
Supported by National Natural Science Foundation of China under Grant Nos.59702011 and 59525101
the 973 State Key Program of Basic Research of China(G1998061314).
