Transport spin polarisation in SrRuO3 measured through Point Contact Andreev reflection

TL;DR

This study measures the transport spin polarization of SrRuO3 using Andreev reflection in high-quality thin films, revealing a large polarization mainly due to differences in Fermi velocities between spin channels.

Contribution

First measurement of transport spin polarization in SrRuO3 using point contact Andreev reflection in the ballistic limit.

Findings

Transport spin polarization is comparable to that of doped manganites.

Large polarization results from Fermi velocity differences between spin channels.

High-quality films enable ballistic regime measurements.

Abstract

We report a study in which Andreev reflection using a Nb point contact is used to measure the transport spin polarisation of the 4d itinerant ferromagnet SrRuO3. By performing the study in high quality thin films with residual resistivities less than 7micro-ohm-cm, we ensure that the study is done in the ballistic limit, a regime which is difficult to reach in oxide ferromagnets. The degree of transport spin polarisation that we find is comparable to that of the hole doped rare-earth manganites. We conclude that the large transport spin polarisation results mainly from a difference in the Fermi velocities between the majority and minority spin channels in this material.