To investigate effects of geometrical frustration on the possibility of superconductivity and its pairing symmetry in the strongly correlated electron system, we calculate the high-temperature series for the equal-time pairing correlation in the two-dimensional t-J model on square and triangular lattices. In the square lattice where the d-wave superconductivity is expected in the ground state, it is found that d-wave pairing correlation really grows with lowering the temperature. In the triangular lattice with t>0, d-wave pairing correlation also shows an enhancement. Since resonating valence bond (RVB)-like behavior is observed in this case, we speculate that the RVB superconductivity is realized. In contrast, in the case of t<0 on the triangular lattice, various pairing symmetries compete with each other. Particularly in the low-density region where the Fermi surface is disconnected, we find the possibility of f-wave superconductivity, which seems to be related to the ferromagnetic tendency in small J region.
- t-J model
- Triangular lattice