paper

Momentum Resolved Superconducting Energy Gaps of SrRuO from Quasiparticle Interference Imaging

arXiv:1912.02798 · doi:10.1073/pnas.1916463117

Abstract

SrRuO 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 on each band that encodes its unknown superconducting order-parameter. But, because the energy scales are so low, it has never been possible to directly measure the of SrRuO. Here we implement Bogoliubov quasiparticle interference (BQPI) imaging, a technique capable of high-precision measurement of multiband . At T=90 mK we visualize a set of Bogoliubov scattering interference wavevectors consistent with eight gap nodes/minima, that are all closely aligned to the crystal-lattice directions on both the -and -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 (2019)), time-reversal symmetry conservation (S. Kashiwaya et al. arXiv:1907.030939) and theory (A.T. Romer et al. Phys. Rev. Lett. 123, 247001 (2019); H. S. Roising et al. Phys. Rev. Research 1, 033108 (2019),O. Gingras et al. Phys. Rev. Lett. 123, 217005 (2019)), the BQPI signature of SrRuO appears most consistent with having symmetry.

arXiv commentaccepted in PNAS

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