Degeneracy between even- and odd-parity superconductivity in the quasi-1D Hubbard model and implications for Sr2RuO4

Abstract

Based on a weak coupling calculation, we show that an accidental degeneracy appears between even- and odd-parity superconductivity in the quasi-1D limit of the repulsive Hubbard model on the square lattice. We propose that this effect could be at play on the quasi-1D orbitals Ru $d_{zx}$ and $d_{zy}$ of Sr2RuO4, leading to a gap of the form $\Delta_\text{even} + i \Delta_\text{odd}$ which could help reconcile several experimental results.