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Theory of Ferromagnetic Metal to Paramagnetic Insulator Transition i in R_{1-x}A_{x}MnO_{3}

L. Sheng·D. N. Sheng·C. S. Ting
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Abstract

The double-exchange model for the Mn oxides with orbital degeneracy is studied with including on-site Coulomb repulsion, Jahn-Teller (J-T) coupling and doping-induced disorder. In the strong interaction limit, it is mapped onto a single-band Anderson model, in which all scattering mechanisms can be treated on an equal footing. A sharp rise in the mean square fluctuation of lattice distortions is found near the Curie temperature $T_c$, in agreement with experiments. We show that the spin and J-T disorders lead to a metal-insulator transition (MIT) only at low carrier density. The MIT observed in samples with $0.2\leq x<0.5$ can be explained by further including the disorder effect of cation size mismatch.

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L. Sheng, D. N. Sheng, C. S. Ting. 1998-11-20. Theory of Ferromagnetic Metal to Paramagnetic Insulator Transition i in R_{1-x}A_{x}MnO_{3}. https://doi.org/10.1103/physrevb.59.13550

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