Pairing symmetry and dominant band inSr2RuO4

Abstract

We study the superconductivity pairing symmetry in Sr2RuO4 in the limit of small interaction by extending a renormalization group calculation developed by Raghu et al. [Phys. Rev. B 81, 224505 (2010)] to include spin-orbit coupling and multiband effects. We show these effects to be crucial to discriminate between the possible order parameters. In contrast to previous results and without the necessity of fine-tuning, we obtain pseudospin-triplet gaps of the same order of magnitude on the two-dimensional γ band and the quasi-one-dimensional α and β bands. The ratio of the gap amplitude on the different bands varies continuously with the interaction parameter. The favored pairing symmetry is shown to be chiral when γ is slightly dominant and helical when α and β are slightly dominant.

Quasiparticle self-consistent GW calculation of Sr2RuO4 and SrRuO3

“…1 and its normal phase is a paramagnetic metal. Its intriguing electronic behavior and superconductivity are still a subject of active study [2][3][4][5][6][7][8][9]. SrRuO 3 (SRO113) is a ferromagnetic metal with a transition temperature of T c ∼ 160 K. The observed magnetic moment is µ= 1.1-1.7 µ B /f.u.…”

Evolution of the filamentary 3-Kelvin phase inPb−Ru−Sr2RuO4Josephson junctions

“…On the other hand, several experimental attempts to observe spontaneous edge currents expected for the chiral p-wave state led to negative results [15][16][17] and have triggered several theoretical studies exploring potential reasons for this conflicting result [18][19][20] . Microscopic calculations concerning the pairing symmetry show a close competition between a chiral and helical p-wave state, the former having inplane-and the latter c-axis equal-spin pairing 21 . Both of these phase are compatible with NMR-data, if we assume that the pinning of the spin configuration by spin-orbit coupling is weak 22,23 .…”

“…Also the observation of half-flux-quantum vortices 24 is probably most easily explained with an almost freely twistable d-vector. On the other hand, recent functional renormalization group studies support the spin triplet pairing dominantly in the γ-band which favors the chiral p-wave channel due to spin-orbit coupling 21,25,26 . In the following we will assume that the bulk superconducting phase of SRO has the chiral p-wave symmetry.…”

Nontopological nature of the edge current in a chiralp-wave superconductor

“…While it remains generically substantial, there is nothing to prevent it from being small, and it can be tuned through zero by varying the band and/or gap-structure. For example, in a model with an anisotropic p-wave order parameter consistent with next-nearest-neighbor (NNN) pairing 40 on the γ band of Sr 2 RuO 4 , the integrated edge current vanishes at a filling fraction close to the experimental value (see Fig. 2).…”