Transport spin polarization in SrRuO3 measured through point-contact Andreev reflection

We report a study in which Andreev reflection using a Nb point contact is used to measure the transport spin polarization of the 4d itinerant ferromagnet SrRuO3 in the ballistic limit of transport. The degree of transport spin polarization is comparable to that of the hole-doped rare-earth manganites. We conclude that the large transport spin polarization results mainly from a difference in the Fermi velocities between the majority- and minority-spin channels in this material.