Abstract
The nature of the superconducting order parameter in Sr2RuO4 has generated intense interest in recent years. Since the superconducting gap is very small, high-resolution methods such as scanning tunneling spectroscopy might be the best chance to directly resolve the gap symmetry. Recently, a Bogoliubov quasiparticle interference imaging (BQPI) experiment has suggested that the dx2-y2 gap symmetry is appropriate for Sr2RuO4. In this work, we use a material-specific theoretical approach based on Wannier functions of the surface of Sr2RuO4 to calculate the continuum density of states as detected in scanning tunneling microscopy experiments. We examine several different proposed gap order parameters and calculate the expected BQPI pattern for each case. Comparing to the available experimental data, our results suggest that a s′+idxy gap order parameter is the most probable state, but the measured BQPI patterns still display features unaccounted for by the theory for any of the states currently under discussion.
| Original language | English |
|---|---|
| Article number | 144505 |
| Journal | Physical Review B |
| Volume | 107 |
| Issue number | 14 |
| DOIs | |
| State | Published - Apr 1 2023 |
Funding
We thank Rahul Sharma and J. C. Davis for sharing experimental data with us and for many helpful discussions that paved the course of the analysis presented in this work. We also thank Ilya Eremin, Marvin Müller, Miguel Sulangi, Roser Valentí, and Karim Zantout for useful discussions. S.B. acknowledges support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through TR 288-422213477. B.M.A. and A.T.R. acknowledge support from the Independent Research Fund Denmark Grant No. 8021-00047B. P.J.H. and S.B. acknowledge partial support from DOE-BES DE-FG02-05ER46236. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility (T.B., X.R.K.). This research also used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DEAC05-00OR22725.