Possible superconductivity in recently discovered (Tl,K)FexSe2 compounds is studied from the viewpoint of doped Mott insulator. The Mott insulating phase is examined to be preferred in the parent compound at x=1.5 due to the presence of Fe vacancies. Partial filling of vacancies at the Fe-sites introduces electron carriers and leads to electron doped superconductivity. By using a two-orbital Hubbard model in the strong coupling limit, we find that the s-wave pairing is more favorable at small Hund's coupling, and dx2−y2 wave pairing is more favorable at large Hund's coupling.
@article{arxiv.1101.4462,
title = {Theory for superconductivity in (Tl,K)Fe$_x$Se$_2$ as a doped Mott insulator},
author = {Yi Zhou and Dong-Hui Xu and Fu-Chun Zhang and Wei-Qiang Chen},
journal= {arXiv preprint arXiv:1101.4462},
year = {2015}
}