Orbital driven two-dome superconducting phases in multiorbital superconductors

Abstract

We theoretically study the superconductivity in multiorbital superconductors based on a three-orbital tight-banding model. With appropriate values of the nearest-neighbor exchange J1αβ and the next-nearest-neighbor exchange J2αβ, we find a two-dome structure in the Tc−n phase diagram: one dome in the doping range n<3.9 where the superconducting (SC) state is mainly sx2y2 component contributed by inter-orbital pairing, the other dome in the doping range 3.9<n<4.46 where the SC state is mainly sx2y2+sx2+y2 components contributed by intra-orbital pairing. We find that the competition between different orbital pairing leads to two-dome SC phase diagrams in multiorbital superconductors, and different matrix elements of J1 and J2 considerably affect the boundary of two SC domes.