1 research outputs found
Superconductivity Driven by the Interband Coulomb Interaction and Implications for the Superconducting Mechanism of MgB2
Superconducting mechanism mediated by interband exchange Coulomb repulsion is
examined in an extended two-band Hubbard models with a wide band crossing the
Fermi level and coexisting with a narrower band located at moderately lower
energy. We apply newly developed path-integral renormalization group method to
reliably calculate pairing correlations. The correlation shows marked
enhancement at moderate amplitudes of the exchange Coulomb repulsion taken
smaller than the on-site repulsion for the narrower band. The pairing symmetry
is s-wave while it has unconventional phases with the opposite sign between the
order parameters on the two bands, in agreement with the mean-field prediction.
Since the band structure of recently discovered superconductor MgB shares
basic similarities with our model, we propose that the present results provide
a relevant clue for the understanding of the superconducting mechanism in
MgB as well as in this class of multi-band materials with good metallic
conduction in the normal state.Comment: 4pages, 2figure