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"Study of phase separation through the charge order to ferromagnetic crossover in (LayPr1-y)0.5Ca0.5MnO3"
J. Curiale, C.A. Ramos, P. Levy, R.D. Sánchez, G. Aurelio and F. Rivadulla
Proc. of the "7th Latin American Workshop on Magnetism, Magnetic Materials and their Applications" (LAW3M-05), Reñaca, Chile, December 12-16, 2005. Ed. J. Rössler, M. Molina and E. Vogel
Physica B Condens. Matter. 384(1-2) (2006) 65-67
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.
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