Properties Of The H-T Phase Diagram Of The 3-K Phase In Eutectic Sr2ruo4-Ru: Evidence For Chiral Superconductivity

We use the Ginzburg-Landau theory for a chiral p-wave superconductor to describe the filamentary superconducting phase nucleating at temperatures higher than the bulk transition temperature near the interfaces between Ru metal and Sr2RuO4 in eutectic Sr2RuO4-Ru. The peculiar phase diagram of magnetic field versus temperature shows very distinct properties for different directions of the magnetic field. A clear feature of the magnetic fields in the basal plane of Sr2RuO4, perpendicular to the chiral axis (c axis), is the occurrence of a second superconducting transition with a new order parameter visible as a zero-bias anomaly in tunneling spectroscopy. For the field along the c axis of Sr2RuO4, two transitions merge, indicating that the field drives the second-order parameter through the paramagnetic coupling to a chiral supercurrent. The resulting phenomenology shows that the assumption of a chiral superconducting order parameter in Sr2RuO4 yields an image reproducing the qualitative properties observed in the experiment. This discussion is qualitatively analogous to the corresponding chiral even- and odd-parity channels.