paper

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

arXiv:2101.06972 · doi:10.1103/PhysRevB.104.064507

Abstract

The symmetry of the superconducting condensate in SrRuO remains controversial after nuclear magnetic resonance (NMR) experiments recently overturned the dominant chiral -wave paradigm. Several theoretical proposals have been put forward to account for existing experiments, including a -wave admixture, conjectured to be stabilized by longer-range Coulomb interactions. We perform a material-specific microscopic theoretical study of pairing by spin- and charge-fluctuations in SrRuO, including the effects of spin-orbit coupling, and both local and longer-range Coulomb repulsion. The latter has important consequences for SrRuO due to the near-degeneracy of symmetry-distinct pairing states in this material. We find that both the - and -wave channels remain noncompetitive compared to leading nodal , , and helical () solutions. This suggests nodal time-reversal symmetry broken or phases, promoted by longer-range Coulomb repulsion, as the most favorable candidates for SrRuO. We analyse the properties of these states, and show that the solution agrees with the bulk of available experimental data, including recent discoveries from NMR, muon spin relaxation (SR), and ultrasound measurements.

4 pages, 2 figures + supplementary material

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