Spin-triplet superconductivity in Sr2RuO4 probed by Andreev reflection

The superconducting gap function of Sr2RuO4 was investigated by means of qu asiparticle reflection and transmission at the normal conductor-superconduc tor interface of Sr2RuO4-Pt point contacts. We found two distinctly differe nt types of dV/dI vs V spectra either with a double-minimum structure or wi th a zero-bias conductance anomaly. Both types of spectra are expected in t he limit of high and low transparency, respectively of the interface barrie r between a normal metal and a spin-triplet superconductor. Together with t he temperature dependence of the spectra this result strongly supports a sp in-triplet superconducting order parameter for Sr2RuO4.