Pairing mechanisms in quasi-two-dimensional organic superconductor

Abstract The superconductivity in organic conductor α - ( BEDT - TTF ) 2 NH 4 Hg ( SCN ) 4 salt, which occurs in the vicinity of charge density wave phase, has been investigated based on the extended Hubbard model described by the transfer integrals obtained from the X-ray experiment. The random phase approximation on the site-representation has been applied to repulsive interactions, which give rise to the pairing mechanism. It is shown that the superconducting transition temperature T c is determined by the charge fluctuation and the pressure dependence of T c with a maximum is consistent with that of the experiment. Discussion is given for the difference in the pairing mechanism between the above salt and α - ( BEDT - TTF ) 2 I 3 salt.