Pairing symmetry in a two-orbital Hubbard model on a square lattice

Abstract

We investigate superconductivity in a two-orbital Hubbard model on a square lattice by applying fluctuation exchange approximation. In the present model, the symmetry of the two orbitals are assumed to be that of an s orbital. Then, we find that an s-wave spin-triplet orbital-antisymmetric state and a p-wave spin-singlet orbital-antisymmetric state appear when Hund's rule coupling is large. These states are prohibited in a single-orbital model within states with even frequency dependence, but allowed for multi-orbital systems. We also discuss pairing symmetry in other models which are equivalent to the two-orbital Hubbard model except for symmetry of orbitals. Finally, we show that pairing states with a finite total momentum, even without a magnetic field, are possible in a system with two Fermi-surfaces.

9 pages, 6 figures

References in corpus (3)

• Orbital ordering phenomena in $d$- and $f$-electron systems
• Ferromagnetic fluctuation and possible triplet superconductivity in Na_xCoO_2*yH_2O: Fluctuation-exchange study of multi-orbital Hubbard model
• Ferromagnetic and triplet-pairing instabilities controlled by the trigonal distortion of the CoO_6 octahedra in Na_xCoO_2*yH_2O

Cited by in corpus (2)

• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Fulde-Ferrell-Larkin-Ovchinnikov State in the absence of a Magnetic Field