Momentum-resolved superconducting energy gaps of Sr2RuO4 from quasiparticle interference imaging

Rahul Sharma, Stephen D. Edkins, Zhenyu Wang, Andrey Kostin, Chanchal Sow, Yoshiteru Maeno, Andrew P. Mackenzie, J. C. Séamus Davis, Vidya Madhavan

Research output: Contribution to journalArticle

Abstract

Sr2RuO4 has long been the focus of intense research interest because of conjectures that it is a correlated topological superconductor. It is the momentum space (k-space) structure of the superconducting energy gap Δi(k) on each band i that encodes its unknown superconducting order parameter. However, because the energy scales are so low, it has never been possible to directly measure the Δi(k) of Sr2RuO4. Here, we implement Bogoliubov quasiparticle interference (BQPI) imaging, a technique capable of high-precision measurement of multiband Δi(k). At T = 90 mK, we visualize a set of Bogoliubov scattering interference wavevectors qj : j = 1 − 5 consistent with eight gap nodes/minima that are all closely aligned to the (±1, ± 1) crystal lattice directions on both the α and β bands. Taking these observations in combination with other very recent advances in directional thermal conductivity [E. Hassinger et al., Phys. Rev. X 7, 011032 (2017)], temperature-dependent Knight shift [A. Pustogow et al., Nature 574, 72–75 (2019)], time-reversal symmetry conservation [S. Kashiwaya et al., Phys. Rev B, 100, 094530 (2019)], and theory [A. T. Rømer et al., Phys. Rev. Lett. 123, 247001 (2019); H. S. Roising, T. Scaffidi, F. Flicker, G. F. Lange, S. H. Simon, Phys. Rev. Res. 1, 033108 (2019); and O. Gingras, R. Nourafkan, A. S. Tremblay, M. Côté, Phys. Rev. Lett. 123, 217005 (2019)], the BQPI signature of Sr2RuO4 appears most consistent with Δi(k) having dx2−y2 (B1g) symmetry.

Original languageEnglish (US)
Pages (from-to)5222-5227
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number10
DOIs
StatePublished - Mar 10 2020

Keywords

  • Quasiparticle interference
  • Strontium ruthenate
  • Superconducting energy gaps

ASJC Scopus subject areas

  • General

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