Our paper on Lu5Rh6Sn18 just came out in PRB as a Rapid Communication:
http://journals.aps.org.chain.kent.ac.uk/prb/abstract/10.1103/PhysRevB.91.060503
In it we report muon spin relaxation evidence for time-reversal symmetry breaking. We also present an analysis of the possible order parameters and quasi-particle spectra for a superconductor with point group D4h under the assumptions of broken time-reversal symmetry and strong spin-orbit coupling (see supplemental material, also available as an appendix in the preprint arxiv version of the paper). This analysis could be relevant also for Sr2RuO4. In the case of Lu5Rh6Sn18 we find that we must have a sort of “hidden” triplet order parameter, in which it has some point nodes which must be prevented from contributing to thermodynamics by the topology of the Fermi surface. Evidently a measurement or a calculation of that Fermmi surface topology would be highly desirable now.
Views from Condensed Matter – by Jorge Quintanilla