An experimental demonstration of room-temperature spin transport in n-type Germanium epilayers

TL;DR

This paper demonstrates for the first time that spin transport can occur at room temperature in n-type germanium epilayers, using spin pumping and inverse spin Hall effect detection.

Contribution

It provides the first experimental evidence of room-temperature spin transport in n-Ge and introduces a theoretical model to estimate spin diffusion length.

Findings

Spin diffusion length in n-Ge is approximately 660 nm.

Room-temperature spin transport is achievable in n-Ge epilayers.

Elliott-Yafet mechanism governs spin relaxation in the material.

Abstract

We report the first experimental demonstration of room-temperature spin transport in n-type Ge epilayers grown on a Si(001) substrate. By utilizing spin pumping under ferromagnetic resonance, which inherently endows a spin battery function for semiconductors connected with the ferromagnet, a pure spin current is generated in the n-Ge at room temperature. The pure spin current is detected by using the inverse spin Hall effect of either Pt or Pd electrode on the n-Ge. A theoretical model including a geometrical contribution allows to estimate a spin diffusion length in n-Ge at room temperature to be 660 nm. The temperature dependence of the spin relaxation time provides evidence for Elliott-Yafet spin relaxation mechanism.