Superconductivity in the vicinity of charge ordered state in organic   conductor beta-(meso-DMBEDT-TTF)_2PF_6
  We study theoretically competition between the charge ordering and the superconductivity in two-dimensional organic conductor beta-(meso-DMBEDT-TTF)_2PF_6. We analyze the extended Hubbard model on a weakly-dimerized lattice based on the random phase approximation and Eliashberg equations. We found reentrant behavior of the checkerbord-type charge-ordered phase in the phase diagram, and the triplet superconductivity due to the charge fluctuation in the neighboring region. In the low temperature and high pressure region, the singlet superconductivity also appears due to the enhancement of the spin fluctuation. 
K.Yoshimi, M.Nakamura, H.Mori