Motivated by the recent discovery of a low temperature spin liquid phase in layered organic compound κ-(ET)2Cu2(CN)3 which becomes a superconductor under pressure, we examine the phase transition of Mott insulating and superconducting (SC) states in a Hubbard-Heisenberg model on an anisotropic triangular lattice. We use a renormalized mean field theory to study the Gutzwiller projected BCS wavefucntions. The half filled electron system is a Mott insulator at large on-site repulsion U, and is a superconductor at a moderate U. The symmetry of the SC state depends on the anisotropy, and is gapful with dx2−y2+idxy symmetry near the isotropic limit and is gapless with dx2−y2 symmetry at small anisotropy ratio.
@article{arxiv.cond-mat/0605214,
title = {Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets},
author = {J. Y. Gan and Yan Chen and F. C. Zhang},
journal= {arXiv preprint arXiv:cond-mat/0605214},
year = {2007}
}