Tunnelling spectroscopy of the interface between Sr2RuO4 and a single Ru micro-inclusion in eutectic crystals

TL;DR

This study investigates the tunnelling spectroscopy of a single interface between Sr2RuO4 and Ru micro-inclusion, revealing the presence of zero bias conductance peaks linked to unconventional superconductivity and time reversal symmetry breaking.

Contribution

It extends previous work by analyzing a single Sr2RuO4/Ru interface, providing deeper insights into the superconducting and symmetry-breaking properties at this interface.

Findings

Observation of zero bias conductance peak (ZBCP) at the interface

Interpretation of ZBCP as due to Andreev bound states

Potential delineation of phase boundary for TRSB state

Abstract

The understanding of the zero bias conductance peak (ZBCP) in the tunnelling spectra of S/N junctions involving d-wave cuprate superconductors has been important in the determination of the phase structure of the superconducting order parameter. In this context, the involvement of a p-wave superconductor such as Sr2RuO4 in tunnelling studies is indeed of great importance. We have recently succeeded in fabricating devices that enable S/N junctions forming at interfaces between Sr2RuO4 and Ru micro-inclusions in eutectic crystals to be investigated.3 We have observed a ZBCP and have interpreted it as due to the Andreev bound state, commonly seen in unconventional superconductors. Also we have proposed that the onset of the ZBCP may be used to delineate the phase boundary for the onset of a time reversal symmetry broken (TRSB) state within the superconducting state, which does not always coincide with the onset of the superconducting state. However, these measurements always involved two interfaces between Sr2RuO4 and Ru. In the present study, we have extended the previous measurements to obtain a deeper insight into the properties of a single interface between Sr2RuO4 and Ru.