Spin Currents injected electrically and thermally from highly spin polarized Co$_2$MnSi

TL;DR

This paper reports the successful injection and detection of electrically and thermally generated spin currents in Co$_2$MnSi/Cu lateral spin valves, revealing high spin polarization and distinct temperature dependencies of the signals.

Contribution

It introduces a comprehensive study of both electrical and thermal spin current generation in Co$_2$MnSi, highlighting the different temperature behaviors and the importance of generation mechanisms.

Findings

Effective spin polarization of 0.63 in Co$_2$MnSi

Spin diffusion length of Cu is 500 nm at room temperature

Different temperature dependences for electrical and thermal signals

Abstract

We demonstrate the injection and detection of electrically and thermally generated spin currents probed in Co$_2$MnSi/Cu lateral spin valves. Devices with different electrode separations are patterned to measure the non-local signal as a function of the electrode spacing and we determine a relatively high effective spin polarization $\alpha$ of Co$_2$MnSi to be 0.63 and the spin diffusion length of Cu to be 500 nm at room temperature. The electrically generated non-local signal is measured as a function of temperature and a maximum signal is observed for a temperature of 80 K. The thermally generated non-local signal is measured as a function of current density and temperature in a second harmonic measurement detection scheme. We find different temperature dependences for the electrically and thermally generated non-local signals, which allows us to conclude that the temperature dependence of the signals is not just dominated by the transport in the Cu wire, but that there is a crucial contribution from the different generation mechanisms, which has been largely disregarded to date.