Unraveling the temperature-dependent spin-polarized electron transport in iron via spin-wave Doppler shift

TL;DR

This study measures how the spin-polarization of electron transport in iron varies with temperature by analyzing the spin-wave Doppler shift, revealing increased polarization at lower temperatures and insights into scattering mechanisms.

Contribution

It provides the first detailed temperature-dependent measurement of spin-polarized electron transport in iron using spin-wave Doppler shift analysis.

Findings

Spin-polarization increases from 77% at 303K to 86% at 10K.

Separates contributions of electron-surface, electron-phonon, and electron-magnon scatterings.

Provides insights into temperature-dependent spin-dependent resistivity in Fe.

Abstract

An electric current flowing in a ferromagnetic metal carries spin angular momentum, i.e. it is spin-polarized. Here, we measure the spin-wave Doppler shift induced by the transfer of angular momentum from the diffusive spin-polarized electric current onto coherent spin waves in epitaxial MgO/Fe/MgO thin films. We follow this Doppler shift as function of the temperature and determine that the degree of spin-polarization of the current increases from 77$\%$ to 86$\%$ when cooling the device from 303K down to 10K. Interpreting these measurements within the two-current model, we separate the contributions from electron-surface, electron-phonon and electron-magnon scatterings to the spin-dependent resistivity of Fe.