Temperature dependence of spin polarization in ferromagnetic metals using lateral spin valves

TL;DR

This study investigates how temperature affects spin polarization in ferromagnetic metals using lateral spin valves, revealing the importance of interface quality and copper purity for reproducible measurements and analyzing temperature-dependent spin properties.

Contribution

It provides a comprehensive analysis of spin injection and transport in ferromagnetic metals and copper, highlighting the need for correction factors in spin polarization measurements.

Findings

Spin polarizations of permalloy and cobalt vary with temperature.

Optimized interface quality improves reproducibility of spin valve performance.

A correction factor of ~2 is necessary for accurate spin polarization values.

Abstract

A high reproducibility in the performance of cobalt/copper and permalloy/copper lateral spin valves with transparent contacts is obtained by optimizing the interface quality and the purity of copper. This allows us to study comprehensively the spin injection properties of both ferromagnetic materials, as well as the spin transport properties of copper, which are not affected by the used ferromagnetic material, leading to long spin diffusion lengths. Spin polarizations of permalloy and cobalt are obtained as a function of temperature. Analysis of the temperature dependence of both the spin polarization and conductivity of permalloy using the standard two-channel model for ferromagnetic metals suggests that a correction factor of ~2 is needed for the spin polarization values obtained by lateral spin valve experiments.