Electronic structure, insulator-metal transition and superconductivity in k-(BEDT-TTF)_2X salts

摘要

The tight-binding approach previously developed for correlated electrons is applied to study k-ET_2X salts. The elctronic energy dispersion relations, density of states, semiconducting gap are calculated. The insulator-metal transition is derived with a phase boundary corresponding to the observed empirical regularity. The symmetry of the obtained electronic transfer is involved in anisotropy and type of the superconducting order parameter for general form of superconducting pairing. It is concluded that the superconducting d_(x~2-y~2)-wave pairing is more preferable.