Edge states of Sr$_2$RuO$_4$ detected by in-plane tunneling spectroscopy

TL;DR

This study uses in-plane tunneling spectroscopy to detect edge states in Sr$_2$RuO$_4$, revealing signatures of topological superconductivity consistent with multiband chiral p-wave symmetry.

Contribution

It provides experimental evidence of edge states in Sr$_2$RuO$_4$ linked to topological superconductivity, supporting the chiral p-wave pairing model.

Findings

Detection of broad humps indicating edge states.

Observation of three peak shapes: domelike, split, and two-step.

Confirmation of multiband chiral p-wave symmetry with weak anisotropy.

Abstract

We perform tunneling spectroscopy of Sr$_2$RuO$_4$ searching for the edge states peculiar to topological superconductivity. Conductance spectra obtained on Sr$_2$RuO$_4$/Au junctions fabricated using $in$ $situ$ process show broad humps indicating the successful detection of a-axis edge of 1.5K phase. Three types of peak shape are detected: domelike peak, split peak and two-step peak. By comparing the experiments with predictions for unconventional superconductivity, these varieties are shown to originate from multiband chiral p-wave symmetry with weak anisotropy of pair amplitude. The broad hump in conductance spectrum is a direct manifestation of the edge state peculiar to the chiral p-wave superconductivity.