MULTIBAND SUPERCONDUCTIVITY - A MAPPING TO THE EXTENDED ATTRACTIVE HUBBARD-MODEL

Following our recent work which shows that purely repulsive multiband systems effectively reduce to the extended attractive Hubbard model having the on-site repulsion along with nearest-neighbor (V) and next-nearst-neighbor (W) attraction for the cuprate structures, we study the latter model in the mean-field theory. T(c) against band filling for various symmetries of pairing is numerically calculated. The results show that, for the region of V and W expected for the mapping from the original multiband model, T(c) has maximum values of the order of 100 K, which is consistent with the experimental results. For certain values of parameters, s- and d(x2-y2)-wave pairing have similar values of T(c), which may suggest the possibility of a mixed phase of the two.