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arXiv · 2007.13730

Evidence for even parity unconventional superconductivity in Sr$_2$RuO$_4$

Aaron Chronister·Andrej Pustogow·Naoki Kikugawa·Dmitry A. Sokolov·Fabian Jerzembeck·Clifford W. Hicks·Andrew P. Mackenzie·Eric D. Bauer·Stuart E. Brown
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Abstract

Unambiguous identification of the superconducting order parameter symmetry of Sr$_2$RuO$_4$ has remained elusive for more than a quarter century. While a chiral $p$-wave ground state analogue to superfluid $^3$He-$A$ was ruled out only very recently, other proposed $p$-wave scenarios are still viable. Here, field-dependent $^{17}$O Knight shift measurements are compared to corresponding specific heat measurements, previously reported. We conclude that the shift results can be accounted for by the expected field-induced quasiparticle response only. An upper bound for the condensate magnetic response of $<10\%$ of the normal state susceptibility is sufficient to exclude odd-parity candidates.

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Aaron Chronister, Andrej Pustogow, Naoki Kikugawa, Dmitry A. Sokolov, Fabian Jerzembeck, Clifford W. Hicks, Andrew P. Mackenzie, Eric D. Bauer, Stuart E. Brown. 2020-07-27. Evidence for even parity unconventional superconductivity in Sr$_2$RuO$_4$. https://doi.org/10.1073/pnas.2025313118

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