Orbital driven two-dome superconducting phases in multiorbital superconductors

TL;DR

This paper theoretically investigates multiorbital superconductors, revealing a two-dome phase diagram driven by orbital competition and exchange interactions, with distinct pairing symmetries in different doping regimes.

Contribution

It introduces a model explaining the two-dome superconducting phases in multiorbital systems based on orbital competition and exchange interactions.

Findings

Two-dome structure in the $T_c$-$n$ phase diagram.

Different pairing symmetries dominate in each dome.

Exchange interactions significantly influence the phase boundaries.

Abstract

We theoretically study the superconductivity in multiorbital superconductors based on a three-orbital tight-banding model. With appropriate values of the nearest-neighbour exchange $J_{1}^{\alpha \beta}$ and the next-nearest-neighbour exchange $J_{2}^{\alpha \beta}$, we find a two-dome structure in the $T_{c}-n$ phase diagram: one dome in the doping range $n<3.9$ where the superconducting (SC) state is mainly $s_{x^{2} y^{2}}$ component contributed by inter-orbital pairing, the other dome in the doping range $3.9<n<4.46$ where the SC state is mainly $s_{x^{2} y^{2}}+s_{x^{2}+y^{2}}$ 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 $J_{1}$ and $J_{2}$ considerably affect the boundary of two SC domes.