A possibility of high-Tc superconductivity on a disconnected Fermi surface in a decorated square lattice

Based on the theory by Kuroki and Arita that disconnected Fermi surfaces are favorable for anisotropic pairing superconductivity mediated by spin fluctuation in repulsively interacting electron systems, we propose here a decorated square lattice, where a four-membered ring forms a unit cell. Estimated Tc indeed turns out to be considerably greater than that of the square lattice. The gap function has curious peaks at Fermi pocket corners, which we identify as an effect of the Cooper pair being formed from a hybridization of molecular orbitals within the unit cell