Variational Monte Carlo study on superconductivity in the anisotropic triangular lattice Hubbard models Original Research Article

We study the single-band Hubbard model at quarter filling defined on the triangular lattices by using the optimization variational Monte Carlo method, whereby we clarify the possible occurrence of superconductivity and its pairing symmetries. We introduce the generalized gap functions which include all the possible spatial symmetries with the nearest-neighbor and next-nearest-neighbor pairings. We find for the isotropic lattice system that a spin-triplet state with a mixed spatial symmetry different from the ordinary f1f1-wave state has the lowest energy in comparison with all the other states including the spin-singlet state as well as the normal state.