Identifying spin-triplet pairing in spin-orbit coupled multi-band superconductors
Department of Physics, University of Toronto - Toronto, Ontario M5S 1A7, Canada
2 Canadian Institute for Advanced Research, Quantum Materials Program - Toronto, Ontario M5G 1Z8, Canada
Accepted: 30 March 2012
We investigate the combined effect of Hund's and spin-orbit (SO) coupling on superconductivity in multi-orbital systems. Hund's interaction leads to orbital-singlet spin-triplet superconductivity, where the Cooper pair wave function is antisymmetric under the exchange of two orbitals. We identify three d-vectors describing even-parity orbital-singlet spin-triplet pairings among t2g-orbitals, and find that the three d-vectors are mutually orthogonal to each other. SO coupling further assists pair formation, pins the orientation of the d-vector triad, and induces spin-singlet pairings with a relative phase difference of π/2. In the band basis the pseudospin d-vectors are aligned along the z-axis and correspond to momentum-dependent inter- and intra-band pairings. We discuss quasiparticle dispersion, magnetic response, collective modes, and experimental consequences in light of the superconductor Sr2RuO4.
PACS: 74.20.-z – Theories and models of superconducting state / 74.20.Rp – Pairing symmetries (other than s-wave) / 74.70.Pq – Ruthenates
© EPLA, 2012