Spin polarization of (Ga,Mn)As measured by Andreev Spectroscopy: The role of spin-active scattering

TL;DR

This study measures the spin polarization of (Ga,Mn)As using Andreev spectroscopy with a new model that considers spin-active scattering, providing more accurate results aligned with theoretical predictions.

Contribution

It introduces a theoretical model for analyzing conductance spectra that accounts for spin-active scattering, improving the accuracy of spin polarization measurements in (Ga,Mn)As.

Findings

Transport polarization of ~57% measured

Better agreement with k·p kinetic-exchange model

Temperature dependence of conductance spectra analyzed

Abstract

We investigate the spin-polarization of the ferromagnetic semiconductor (Ga,Mn)As by point contact Andreev reflection spectroscopy. The conductance spectra are analyzed using a recent theoretical model that accounts for momentum- and spin-dependent scattering at the interface. This allows us to fit the data without resorting, as in the case of the standard spin-dependent Blonder-Tinkham-Klapwijk (BTK) model, to an effective temperature or a statistical distribution of superconducting gaps. We find a transport polarization PC{\approx}57%, in considerably better agreement with the k{\cdot}p kinetic-exchange model of (Ga,Mn)As, than the significantly larger estimates inferred from the BTK model. The temperature dependence of the conductance spectra is fully analyzed.