Magnetic properties and colossal magnetoresistance of the perovskites La2/3Ca1/3Mn1-xTixO3

Structure, magnetic, and transport properties of the compounds La2/3Ca1/3Mn1-xTixO3(0 less than or equal to x less than or equal to 0.3) have been investigated. The substitution of a Ti4+ ion for a Mn4+ ion suppresses the ferromagnetism and metallic conduction significantly. In the case of low doping (x less than or equal to 0.04), Curie temperature T-C decreases linearly with the substitution at a rate of about 31 K for 1% Ti. The magnetic spontaneous state has become a cluster glass state for the sample where x = 0.06. Corresponding to the decrease of T-C, the metal-insulator transition temperature and the peak of magnetoresistance (MR) shift to low temperature, while the resistivity and the maximum of MR increase with increasing Ti concentration. The magnetic dilution should be responsible for the experimental results. (C) 2000 American Institute of Physics. [S0021-8979(00)41608-7].