Spin Density Wave and Superconductivity in Highly Anisotropic Materials. II. Detailed Study of Phase Transitions

Abstract
Within the mean field approximation the free energy is calculated for a system which has two kinds of long range order parameters, the superconducting (SC) order Δ and spin density wave (SDW) order M . The phase diagrams representing the SC, SDW and their coexistence states are derived under various conditions for the model parameters. Thermodynamic quantities such as the specific heat, entropy change and critical field are also evaluated near the transition points. Discussions on possible phase diagrams for (TMTSF) 2 PF 6 under pressure are given.