Magnetic behavior of the La1-yCayMn1-xFexO3 perovskites

The magnetic ordering of the compounds La1-yCayMn1-xFexO3 where 0.2 <y <0.5 and 0 <x <0.1 has been studied within the molecular field theory. We intro duce a model based on the competition between ferromagnetic coupling betwee n the Mn ions and strong antiferromagnetic coupling induced by the presence of Fe ions. The magnetization as a function of temperature and the critica l temperature have been calculated for several values of the parameter x. W e show that even for very small x, the magnetic order of the system is redu ced. Our results are in good agreement with experimental findings on these systems. (C) 2000 American Institute of Physics. [S0003-6951(00)03248-4].