Estimation of the spin polarization for Heusler-compound thin films by means of nonlocal spin-valve measurements: Comparison of Co$_{2}$FeSi and Fe$_{3}$Si

TL;DR

This study measures and compares the spin polarization of Co2FeSi and Fe3Si Heusler-compound thin films using nonlocal spin-valve devices at room temperature, revealing the influence of resistivity and structural order.

Contribution

It demonstrates how resistivity and structural ordering affect spin polarization in Heusler compounds, with a comparative analysis of Co2FeSi and Fe3Si.

Findings

Spin polarization increases as resistivity decreases.

Co2FeSi exhibits higher spin polarization than Fe3Si.

Resistivity dispersion impacts spin signal magnitude.

Abstract

We study room-temperature generation and detection of pure spin currents using lateral spin-valve devices with Heusler-compound electrodes, Co$_{2}$FeSi (CFS) or Fe$_{3}$Si (FS). The magnitude of the nonlocal spin-valve (NLSV) signals is seriously affected by the dispersion of the resistivity peculiarly observed in the low-temperature grown Heusler compounds with ordered structures. From the analysis based on the one-dimensional spin diffusion model, we find that the spin polarization monotonically increases with decreasing the resistivity, which depends on the structural ordering, for both CFS and FS electrodes, and verify that CFS has relatively large spin polarization compared with FS.