Study of phase separation through the charge order to ferromagnetic crossover in (La1-yPry)0.5Ca0.5MnO3

CURIALE, J.; RAMOS, C. A.; LEVY, P.; SÁNCHEZ, R. D.; AURELIO, G.; RIVADULLA, F.

Reñaca, Chile

Workshop; Latin American Workshop on Magnetism, Magnetic Materials and their applications; 2005

We present a magnetic phase diagram for the (LayPr1-y)0,5Ca0,5MnO3 family with different degrees of La–Pr substitution (y) based on electric resistivity, magnetization, X-ray diffraction at different temperatures and thermal expansion experiments. In this series, the structural distortion due to the variation of the mean ionic radius of site A (rA), by decreasing y, induces a rapid diminution of the ferromagnetic (FM) Curie temperature (TC) and an increase of the charge-order (CO) temperature (TCO). The crossover between TC and TCO determines a critical tolerance factor (tc=0.975), which is consistent with previous reports on other manganites with the same Mn3+/Mn4+ ratio. For tolerance factors close to tc, we observe the coexistence of different amounts of FM and CO phases depending on y. The disorder introduced by y and the presence of phase separation around tc induces a smooth and continuous variation of the structural, electrical and magnetic properties when crossing through tc.