Spin injection in Silicon at zero magnetic field

TL;DR

This paper demonstrates efficient electrical spin injection into silicon-based LEDs using a remanent ferromagnetic contact, achieving measurable light polarization without external magnetic fields, and maintaining polarization up to 200 K.

Contribution

It introduces a method for spin injection into silicon devices using remanent magnetization, eliminating the need for external magnetic fields, with stable polarization at higher temperatures.

Findings

Achieved 3% circular polarization at 5 K

Polarization remains stable up to 200 K

Demonstrated spin injection without external magnetic field

Abstract

In this letter, we show efficient electrical spin injection into a SiGe based \textit{p-i-n} light emitting diode from the remanent state of a perpendicularly magnetized ferromagnetic contact. Electron spin injection is carried out through an alumina tunnel barrier from a Co/Pt thin film exhibiting a strong out-of-plane anisotropy. The electrons spin polarization is then analysed through the circular polarization of emitted light. All the light polarization measurements are performed without an external applied magnetic field \textit{i.e.} in remanent magnetic states. The light polarization as a function of the magnetic field closely traces the out-of-plane magnetization of the Co/Pt injector. We could achieve a circular polarization degree of the emitted light of 3 % at 5 K. Moreover this light polarization remains almost constant at least up to 200 K.