Spectroscopy of Sr2RuO4/Ru Junctions in Eutectic

We have investigated the tunnelling properties of the interface between superconducting Sr2RuO4 and a single Ru inclusion in eutectic. By using a micro‐fabrication technique, we have made Sr2RuO4/Ru junctions on the eutectic system that consists of Sr2RuO4 and Ru micro‐inclusions. Such a eutectic system exhibits surface superconductivity, called the 3‐K phase. A zero bias conductance peak (ZBCP) was observed in the 3‐K phase. We propose to use the onset of the ZBCP to delineate the phase boundary of a time‐reversal symmetry breaking state.