The role of spin-orbit coupling for the superconducting state in Sr₂RuO₄

The odd-parity spin-triplet Cooper pairing states show a six-fold degeneracy for a quasi-two-dimensional electron system. In this article we show how spin-orbit coupling can lift this degeneracy for Sr_2RuO_4 taking the band structure based on the three relevant t_{2g}-orbitals of the Ru-ions into account. The stabilized state depends on the relative strength of the pairing interaction. We show that under reasonable assumptions the chiral pairing state d(k) = z(k_x +/- i k_y) is favored against the others.