Energy gap structure in spin density wave superconductors

Abstract

The superconducting density of states is investigated theoretically for the coexistence phase of a spin density wave (SDW) and superconducting (SC) states on the basis of an anisotropic electron band model within the mean field approximation. The energy gap structure markedly differs from the ordinary BCS superconductor. The superconducting tunneling experiment on an organic conductor (TMTSF) 2 PF 6 under a pressure P = 11 k bar is discussed in this connection, with the conclusion that the observed anomalously large superconducting gap comes mainly from the SDW, which implies the SDW and SC coexist at low temperatures.