Off-site repulsion-induced triplet superconductivity: a possibility for chiral p(x+y)-wave pairing in Sr2RuO4

In order to probe the effect of charge fluctuations on triplet pairing, we study the pairing symmetry in the one-band Hubbard model having the off-site Coulomb repulsion (V) on top of the on-site repulsion as a model for the gamma band of Sr2RuO4, a strong candidate for a triplet pairing superconductor. The result, obtained with the dynamical cluster approximation combined with the quantum Monte Carlo method, and confirmed from the fluctuation exchange approximation, shows that while d(x(2)-y(2)) pairing dominates over p in the absence of V, introduction of V makes p(x+y) and d(xy) dominant. The gap function for the chiral p(x+y)+ip(x-y) has nodes that are consistent with the recent measurement of specific heat in rotated magnetic fields in the ruthenate. This suggests that the off-site repulsion may play an essential role in triplet superconductivity in this material.