Lateral Spin Injection in Germanium Nanowires

TL;DR

This paper demonstrates lateral spin injection and detection in germanium nanowires using ferromagnetic contacts, revealing a spin diffusion length exceeding 100 micrometers at low temperature, which advances spintronic device integration.

Contribution

It introduces a method for lateral spin injection in germanium nanowires with detailed contact resistance mapping and confirms a long spin diffusion length using spin diffusion theory.

Findings

Lateral spin transport observed in germanium nanowires

Spin diffusion length exceeds 100 μm at 4.2 K

Contact resistance window for effective spin injection identified

Abstract

Electrical injection of spin-polarized electrons into a semiconductor, large spin diffusion length, and an integration friendly platform are desirable ingredients for spin-based devices. Here we demonstrate lateral spin injection and detection in germanium nanowires, by using ferromagnetic metal contacts and tunnel barriers for contact resistance engineering. Using data measured from over 80 samples, we map out the contact resistance window for which lateral spin transport is observed, manifestly showing the conductivity matching required for spin injection. Our analysis, based on the spin diffusion theory, indicates that the spin diffusion length is larger than 100 {\mu}m in germanium nanowires at 4.2 K.