Spin accumulation created electrically in an n-type germanium channel using Schottky tunnel contacts

TL;DR

This study demonstrates electrical creation and detection of spin accumulation in an n-type germanium channel using Schottky tunnel contacts, revealing shorter spin lifetimes and challenging existing diffusion models at 50 K.

Contribution

First demonstration of spin accumulation in n-type germanium using Fe3Si/n+-Ge Schottky contacts with detailed analysis of spin lifetime and detection signals.

Findings

Hanle-effect signals detected at forward-biased contact

Spin lifetime in n-Ge at 50 K is shorter than in n-Si

Observed spin signals exceed predictions of standard diffusion models

Abstract

Using high-quality Fe$_{3}$Si/$n^{+}$-Ge Schottky-tunnel-barrier contacts, we study spin accumulation in an $n$-type germanium ($n$-Ge) channel. In the three- or two-terminal voltage measurements with low bias current conditions at 50 K, Hanle-effect signals are clearly detected only at a forward-biased contact. These are reliable evidence for electrical detection of the spin accumulation created in the $n$-Ge channel. The estimated spin lifetime in $n$-Ge at 50 K is one order of magnitude shorter than those in $n$-Si reported recently. The magnitude of the spin signals cannot be explained by the commonly used spin diffusion model. We discuss a possible origin of the difference between experimental data and theoretical values.