Measurement of Spin Polarization by Andreev Reflection in Ferromagnetic In1-xMnxSb Epilayers

TL;DR

This study used Point Contact Andreev Reflection to measure spin polarization in ferromagnetic In1-xMnxSb epilayers, demonstrating a polarization of approximately 52%, and validated the method with control experiments on a non-magnetic analog.

Contribution

It provides the first direct measurement of spin polarization in ferromagnetic In1-xMnxSb using PCAR, with validation through control experiments on a non-magnetic analog.

Findings

Spin polarization in In1-xMnxSb is approximately 52%.

Control experiments on In1-yBeySb show conventional conductance curves.

Interfacial scattering Z-values match theoretical estimates.

Abstract

We carried out Point Contact Andreev Reflection (PCAR) spin spectroscopy measurements on epitaxially-grown ferromagnetic In1-xMnxSb epilayers with a Curie temperature of ~9K. The spin sensitivity of PCAR in this material was demonstrated by parallel control studies on its non-magnetic analog, In1-yBeySb. We found the conductance curves of the Sn point contacts with In1-yBeySb to be fairly conventional, with the possible presence of proximity-induced superconductivity effects at the lowest temperatures. The experimental Z-values of interfacial scattering agreed well with the estimates based on the Fermi velocity mismatch between the semiconductor and the superconductor. These measurements provided control data for subsequent PCAR measurements on ferromagnetic In1-xMnxSb, which indicated spin polarization in In1-xMnxSb to be 52 +- 3%.