Characteristics of magnetic order in perovskite manganites La1-xCaxMnO3

Solid solutions of the system La1-xCaxMnO3 are synthesized, and their magne tic and electrical properties are investigated. As x is increased, the crys tal lattice changes symmetrically from an orthorhombic (x = 0 and x = 0.8) to a cubic structure (0 < x less than or equal to 0.6 and x = 1). Nonstoich iometric LaMnO3 and compositions with a low Ca content (0 < x < 0.4) are co llinear ferromagnets. A metal-insulator transition is observed in them near the Curie temperature. Compositions with 0.6 less than or equal to x less than or equal to 0.9 exhibit a semiconductor-type conductivity and an unusu al temperature behavior of the magnetization and the susceptibility with ve ry distinct Curie and Neel temperatures. The magnetic properties of the sol id solutions are explained on the basis of the model of ferro-antiferromagn etic phase separation. (C) 1999 American Institute of Physics. [S1063-7761( 99)01211-1].