Metal-insulator transitions: Influence of lattice structure, Jahn-Teller effect, and Hund's rule coupling

Abstract

We study the influence of the lattice structure, the Jahn-Teller effect and the Hund's rule coupling on a metal-insulator transition in AnC60 (A= K, Rb). The difference in lattice structure favors A3C60 (fcc) being a metal and A4C60 (bct) being an insulator, and the coupling to Hg Jahn-Teller phonons favors A4C60 being nonmagnetic. The coupling to Hg (Ag) phonons decreases (increases) the value Uc of the Coulomb integral at which the metal-insulator transition occurs. There is an important partial cancellation between the Jahn-Teller effect and the Hund's rule coupling.

4 pages, RevTeX, 3 eps figure, additional material available at http://www.mpi-stuttgart.mpg.de/docs/ANDERSEN/fullerene/

References in corpus (7)

• Non magnetic molecular Jahn-Teller Mott insulators
• Multi-Orbital Hubbard Model in Infinite Dimensions: Quantum Monte Carlo Calculation
• Screening, Coulomb pseudopotential, and superconductivity in alkali-doped Fullerenes
• Mott-Hubbard insulators for systems with orbital degeneracy
• Filling dependence of the Mott transition in the degenerate Hubbard model
• Important role of alkali atoms in A4C60
• Hubbard model with orbital degeneracy and integer or noninteger filling

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