Mott transition and superconductivity in alkali-doped fullerides.

Gunnarsson O., Koch E., Martin R.M.

Max-Planck-Institut für Festkörperforschung, D-70506 Stuttgart, Germany;
Department of Physics, University of Illinois, Urbana, Illinois 6180

We study the effects of deviations from cubic symmetry on superconductivity and on Mott transitions by comparing A3C60 and NH3K3C60. The reduced frustration in NH3K3C60 favours a Mott transition at a lower ratio U/W, where U is the Coulomb repulsion of two electrons on the same molecule and W is the width of the t1u band. The closeness of NH3K3C60 to a Mott transition may influence the superconductivity negatively, due to an inefficient screening of the Coulomb repulsion.

in: Electronic Properties of novel Materials. Eds. H. Kuzmany, J. Fink, M. Mehring, S. Roth. Woodbury, NY: AIP, 287-291 (CP442) (1998 Kirchberg Winterschool Proc.).

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