Even-parity spin-triplet pairing by purely repulsive interactions for orbitally degenerate correlated fermions

Abstract

We demonstrate the stability of the spin-triplet paired s-wave (with an admixture of extended s-wave) state for the limit of purely repulsive interactions in a degenerate two-band Hubbard model of correlated fermions. The repulsive interactions limit represents an essential extension of our previous analysis (2013 New J. Phys. 15 073050), regarded here as I. We also show that near the half-filling the considered type of superconductivity can coexist with antiferromagnetism. The calculations have been carried out with the use of the so-called statistically consistent Gutzwiller approximation (SGA) for the case of a square lattice. We suggest that the electron correlations in conjunction with the Hund's rule exchange play the crucial role in stabilizing the real-space spin-triplet superconducting state. A sizable hybridization of the bands suppresses the homogeneous paired state.

Keywords

• correlated fermions
• orbitally degenerate Hubbard model
• spin-triplet superconductivity
• Hund's rule pairing
• antiferromagnetism-superconductivity coexistence
• even-parity spin-triplet pairing