METAL-INSULATOR TRANSITIONS IN DEGENERATE HUBBARD MODELS AND AXC60

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关键词: ELECTRONIC-TRANSPORT-PROPERTIES;    ALKALI-METAL;    ORIENTATIONAL DISORDER;    PHASE-TRANSITIONS;    SOLID C-60;    K3C60;    FULLERIDES;    STATE;    INTERCALATION;    LOCALIZATION;   

DOI  :  10.1103/PhysRevB.49.5687

来源: SCIE

【 摘 要 】

Analytic results for Mott-Hubbard metal-insulator transitions in N-fold degenerate Hubbard models are obtained using the Gutzwiller approximation. It is found that for any commensurate filling with integer (x) electrons per site, there exists a metal-insulator transition at the critical correlation energy U(c)(N,x)={[square-root x(2N - x + 1) + square-root (x + 1)(2N - X)]2/(2N - x)}\epsilon(x)BAR\, where epsilonBAR is the energy per particle in the absence of correlation. U(c) increases with x reaching the maximum at the half filling x = N. Therefore, it is possible for a system to be metallic at half filling and insulating away from half filling. This provides an explanation for the unusual metal-insulator transitions observed in fullerides A(x)C60.

【 授权许可】

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