Superconducting state of Sr2RuO4 in the presence of longer-range Coulomb interactions

The symmetry of the superconducting condensate in Sr2RuO4 remains controversial after recent experiments overturned the dominant chiral p-wave paradigm. We perform a theoretical study of pairing by spin- and chargefluctuations in Sr2RuO4, including the effects of spin-orbit coupling, and both local and longer-range Coulomb repulsion. The latter has important consequences for Sr2RuO4 due to the near-degeneracy of symmetry-distinct pairing states in this material. We find leading nodal s', d(xy), and helical (p) solutions, while both the g- and d(x2-y2)-wave channels remain noncompetitive. This suggests nodal time-reversal symmetry broken s'+ id(xy) or s,+ ip phases, promoted by longer-range Coulomb repulsion, as the most favorable candidates for Sr2RuO4. We analyze the properties of these states and show that the s'+ id(xy) solution agrees with the bulk of available experimental data.

Automated summary

The symmetry of the superconducting condensate in Sr2RuO4 remains controversial, with recent experiments overturning the dominant paradigm and suggesting that s'+ id(xy) or s,+ ip phases may be the most favorable candidate states.