We compute and compare even- and odd-parity superconducting order parameters of strontium ruthenate (Sr2RuO4) in the limit of weak interactions, resulting from a fully microscopic three-dimensional model including spin-orbit coupling. We find that odd-parity helical and even-parity d-wave order are favored for smaller and larger values of the Hund's coupling parameter J, respectively. Both orders are found compatible with specific heat data and the recently-reported nuclear magnetic resonance (NMR) Knight shift drop [A. Pustogow et al. Nature 574, 72 (2019)]. The chiral p-wave order, numerically very competitive with helical order, sharply conflicts with the NMR experiment.
@article{arxiv.1907.09485,
title = {Superconducting order of $\mathrm{Sr}_2\mathrm{RuO}_4$ from a three-dimensional microscopic model},
author = {Henrik S. Røising and Thomas Scaffidi and Felix Flicker and Gunnar F. Lange and Steven H. Simon},
journal= {arXiv preprint arXiv:1907.09485},
year = {2019}
}