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Theory of the Metal-Paramagnetic Mott-Jahn-Teller Insulator Transition in A_4C_{60}

M. Capone·M. Fabrizio·P. Giannozzi·E. Tosatti
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Abstract

We study the unconventional insulating state in A_4C_{60} with a variety of approaches, including density functional calculations and dynamical mean-field theory. While the former predicts a metallic state, in disagreement with experiment, the latter yields a (paramagnetic) Mott-Jahn-Teller insulator. In that state, conduction between molecules is blocked by on-site Coulomb repulsion, magnetism is suppressed by intra-molecular Jahn-Teller effect, and important excitations (such as optical and spin gap) should be essentially intra-molecular. Experimental gaps of 0.5 eV and 0.1 eV respectively compare well with molecular ion values, in agreement with this picture.

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M. Capone, M. Fabrizio, P. Giannozzi, E. Tosatti. 1999-05-12. Theory of the Metal-Paramagnetic Mott-Jahn-Teller Insulator Transition in A_4C_{60}. https://doi.org/10.1103/physrevb.62.7619

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