Dr. Stuart Brown, UCLA Physics and Astronomy
When
Where
Abstract: Sr2RuO4 (SRO) is a layered perovskite, isomorphic to La2CuO4, and first found to be superconducting shortly after the discovery of the high-Tc copper oxides. However, unlike the cuprates and many other unconventional superconductors, SRO is stoichiometric, can be synthesized very clean, and exhibits low temperature properties of a Fermi Liquid. While the superconducting state is decidedly unconventional, a determination of the pairing symmetry has remained uncomfortably elusive given such a well-defined theoretical starting point. It wasn’t always the case: considerable interest in the problem was enhanced as a result of the topological nature of the triplet pairing state persistently advocated for [1]. All that has changed [2]. We present contrary and conclusive evidence from NMR measurements for a non-topological state [3], and summarize the status given other important developments in experiment as well as theoretical models, including evidence for a two-component order parameter and concomitant time reversal symmetry breaking.
[1] Andrew P. Mackenzie, et al., npj Quantum Materials 2, 40 (2017).
[2] Andrej Pustogow, et al., Nature 574, 72-75 (2019).
[3] Aaron Chronister, et al., arXiv:2007.13730.