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TT: Fachverband Tiefe Temperaturen
TT 22: Unconventional Superconductors
TT 22.4: Vortrag
Mittwoch, 7. September 2022, 16:00–16:15, H10
Spin-fluctuation pairing and Hund’s pairing in Sr2RuO4 — Mercè Roig1, Astrid T. Rømer1, Thomas A. Maier2, •Andreas Kreisel3, Peter J. Hirschfeld4, and Brian M. Andersen1 — 1Niels Bohr Institute, University of Copenhagen — 2Center for Nanophase Materials Sciences, Oak Ridge National Laboratory — 3Institut für Theoretische Physik, Universität Leipzig — 4Department of Physics, University of Florida
The unconventional superconductor Sr2RuO4 has been subject of enormous experimental investigations in the last two decades, but until now the form of its order parameter has not been explicitly determined. Given the exclusion of spin-triplet superconductivity by recent experiments, the time-reversal symmetry breaking linear combinations of s-, d- and g-wave one-dimensional (1D) irreducible representations are strong candidates. However, also a two-dimensional representation Eg, stabilized within the so-called Hund’s coupling mean-field pairing scenario, has been proposed. In this work, we examine Hund’s pairing on equal footing with spin-fluctuation pairing using a three dimensional electronic structure for Sr2RuO4 and a model that does not exhibit clear nesting features. For the latter, the superconducting state generated by the Hund’s mechanism agrees well with that from the full fluctuation exchange vertex for large J/U ratios. On the other hand, for systems characterized by a peaked finite-momentum susceptibility, spin-fluctuation pairing generally dominates over Hund’s pairing. We conclude that Hund’s pairing states (and therefore also the Eg pairing) are unlikely to be realized in systems like Sr2RuO4.