Investigation of spin scattering mechanism in silicon channels of Fe/MgO/Si lateral spin valves

TL;DR

This study investigates the temperature-dependent spin relaxation in silicon-based lateral spin valves, revealing that the dominant spin scattering mechanism is Elliott-Yafet, with minimal magnetic impurity influence, and provides detailed quantitative analysis.

Contribution

It provides the first detailed temperature evolution of spin relaxation time in silicon lateral spin valves and identifies the dominant scattering mechanism as Elliott-Yafet.

Findings

Spin relaxation time increases from 1.68 ns at 300 K to ~5 ns below 100 K.

Electron scattering due to magnetic impurities is negligible.

The ratio of momentum to spin relaxation time is significantly smaller than in copper.

Abstract

The temperature evolution of spin relaxation time, {\tau}sf, in degenerate silicon (Si)-based lateral spin valves is investigated by means of the Hanle effect measurements. {\tau}sf at 300 K is estimated to be 1.68+-0.03 ns and monotonically increased with decreasing temperature down to 100 K. Below 100 K, in contrast, it shows almost a constant value of ca. 5 ns. The temperature dependence of the conductivity of the Si channel shows a similar behavior to that of the {\tau}sf, i.e., monotonically increasing with decreasing temperature down to 100 K and a weak temperature dependence below 100 K. The temperature evolution of conductivity reveals that electron scattering due to magnetic impurities is negligible. A comparison between {\tau}sf and momentum scattering time reveals that the dominant spin scattering mechanism in the Si is the Elliott-Yafet mechanism, and the ratio of the momentum scattering time to the {\tau}sf attributed to nonmagnetic impurities is approximately 3.77*10^-6, which is more than two orders of magnitude smaller than that of copper.