Possible spin-triplet f-wave pairing due to disconnected Fermi surfaces in NaxCoO2•yH2O -: art. no. 077001

We propose that the spin-triplet pairing mechanism due to disconnected Fermi surfaces proposed in our previous study [Phys. Rev. B 63, 174507 (2001)] may be at work in a recently discovered superconductor NaxCoO2.yH(2)O. We introduce a single band effective model that takes into account the pocketlike Fermi surfaces along with the van Hove singularity near the K point found in the band calculation results. Applying the fluctuation exchange method and solving the linearized Eliashberg equation, the most dominant pairing is found to have spin-triplet f-wave symmetry, where the nodes of the gap function do not intersect the pocket Fermi surfaces. The presence of finite T-c is suggested in sharp contrast to cases when the gap nodes intersect the Fermi surface.