Metallicity, susceptibility and superconductivity in A3C60 (A=K, Rb).

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

Max-Planck-Institut für Festkörperforschung, Stuttgart;
Department of Physics, University of Illinois, Urbana, Illinois 6180;
Department of Theoretical Physics, University of Lund, S-223 62 Lund, Sweden

We study the condition for a Mott-Hubbard metal-insulator transition. We find that the orbital degeneracy N shifts the critical value of the Coulomb interaction where the transition takes place by a factor of the order of square root N. This explains why A3C60 (A=K, Rb) are metals. We furthermore calculate the Pauli susceptibility chi . From the calculated many-body enhancement and experimental values of chi , we deduce the density of states. Finally, we discuss the strength of the electron-phonon interaction and the superconductivity.

Electrochemical Society Proceedings 97-14, 1040-1054.

Max-Planck Institut für Festkörperforschung;
Postfach 80 06 65   D-70506 Stuttgart