Differential resistance measurements are conducted for point contacts (PCs) between tungsten tip approaching along the c axis direction and the ab plane of Sr2RuO4 single crystal. Three key features are found. Firstly, within 0.2 mV there is a dome like conductance enhancement due to Andreev reflection at the normal-superconducting interface. By pushing the W tip further, the conductance enhancement increases from 3% to more than 20%, much larger than that was previously reported, probably due to the pressure exerted by the tip. Secondly, there are also superconducting like features at bias higher than 0.2 mV which persists up to 6.2 K, resembling the enhanced superconductivity under uniaxial pressure for bulk Sr2RuO4 crystals but more pronounced here. Third, the logarithmic background can be fitted with the Altshuler-Aronov theory of tunneling into quasi two dimensional electron system, consistent with the highly anisotropic electronic system in Sr2RuO4.The layered perovskite ruthenate Sr 2 RuO 4 (SRO) has shown evidence for spin-triplet, odd-parity superconductivity (SC) which may be useful for topological quantum computation.

Sr 2 RuO 4 (SRO) is the prime candidate for a chiral p-wave superconductor with critical temperaturẽ ( ) T SRO 1.5 c K. Chiral domains with opposite chiralities  p p i x y have been proposed, but are yet to be confirmed. We measure the field dependence of the point contact (PC) resistance between a tungsten tip and an SRO-Ru eutectic crystal, where micrometer-sized Ru inclusions are embedded in SRO with an atomically sharp interface. Ruthenium is an s-wave superconductor with( ) T Ru 0.5 c K; flux pinned near the Ru inclusions can suppress its superconductivity, as reflected in the PC resistance and spectra. This flux pinning effect originates from SRO underneath the surface and is very strong once flux is introduced. To fully remove flux pinning, one needs to thermally cycle the sample above T c (SRO) or apply alternating fields with decreasing amplitude. With alternating fields, the observed hysteresis in magnetoresistance can be explained by domain dynamics, providing support for the existence of chiral domains. The origin of the strong pinning could be the chiral domains themselves.