Measurements of Spin Polarization of Epitaxial SrRuO3 Thin Films

TL;DR

This paper reports the measurement of transport spin polarization in epitaxial SrRuO3 thin films using PCAR, revealing a significant polarization of about 50% despite similar densities of states for spin channels.

Contribution

It provides the first experimental measurement of transport spin polarization in SrRuO3 thin films and links it to Fermi velocity disparities, confirming theoretical predictions.

Findings

Transport spin polarization is about 50%.

Fermi velocity disparity explains the polarization.

Results agree with theoretical estimates.

Abstract

We have measured the transport spin-polarization of epitaxial thin films of the conductive ferromagnetic oxide, SrRuO3, using Point Contact Andreev Reflection Spectroscopy (PCAR). In spite of the fact that spin-up and spin-down electronic densities of states at the Fermi level for SrRuO3 calculated from band structure theory are practically the same, the experimental transport spin polarization for these films was found to be about 50%. This result is a direct consequence of the Fermi velocity disparity between the majority and minority bands and is in good agreement with our theoretical estimates.