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High-Pressure Phase Diagram in the Manganites: a Two-site Model Study

Research paper by A. Sacchetti, P. Postorino, M. Capone

Indexed on: 10 Feb '04Published on: 10 Feb '04Published in: Physics - Strongly Correlated Electrons



Abstract

The pressure dependence of the Curie temperature $T_C$ in manganites, recently studied over a wide pressure range, is not quantitatively accounted for by the quenching of Jahn-Teller distortions, and suggests the occurrence of a new pressure-activated localizing processes. We present a theoretical calculation of $T_C$ based on a two-site double-exchange model with electron-phonon coupling interaction and direct superexchange between the $% t_{2g}$ core spins. We calculate the pressure dependence of $T_C$ and compare it with the experimental phase diagram. Our results describe the experimental behavior quite well if a pressure-activated enhancement of the antiferromagnetic superexchange interaction is assumed.