O. Gunnarsson(1), E. Koch (1,2) and R.M. Martin(2)
(1) Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
(2) Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Il 61801
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.
A postscript file is available at this http URL
Electronic Properties of novel Materials - Progress in molecular
nanostructures, Eds. H. Kuzmany,
J. Fink, M. Mehring, and S. Roth, AIP Conference Proceedings 442,
(Woodbury, New York, 1998), p. 287.
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