EFFECTS OF CHEMICAL PRESSURE ON FERROMAGNETISM AND TRANSPORT PROPERTIES IN La0.7-xYxCa0.3CoO3

We have investigated the chemical pressure effects, induced by the substitution of smaller ionic radius Y3+ for La3+, on the magnetic and electrical transport properties for the La0.7-xYxCa0.3CoO3 (x = 0, 0.05, 0.1, and 0.15). The magnetization and the Curie temperature TC decrease sharply as the doping level of Y3+ increases, which indicates that the chemical pressure induced by Y3+-doping can suppress the ferromagnetism. The transport measurement reveals a chemical pressure-induced increase of the resistivity due to a suppression of eg-electron hopping. We thought that the effect of Y3+-doping induced chemical pressure on the ferromagnetic (FM) phase has a similar behavior to that of external pressure. These results imply that the enhancing chemical pressure can suppress the FM phase in La0.7-xYxCa0.3CoO3.