Electrical detection of optically pumped spin polarization in Ge

TL;DR

This paper demonstrates room temperature detection of photon helicity at 1300 nm using spin- photodiodes based on epitaxial Fe/MgO/Ge heterostructures, enabling optical spin detection in germanium.

Contribution

It introduces a novel integrated spin-photodiode device capable of detecting photon helicity at room temperature in germanium-based heterostructures.

Findings

Achieved 5.9% photocurrent variation for circularly polarized light.

Identified contributions of 0.8% from Fe dichroic absorption and 5.1% from spin filtering.

Demonstrated effective helicity detection at 1300 nm wavelength.

Abstract

Here we show the room temperature integrated detection of the helicity of photons with 1300 nm wavelength, via spin- photodiodes based on fully epitaxial Fe/MgO/Ge(001) heterostructures. These devices convert the photon helicity in a variation of the photocurrent ({\Delta}I) for opposite orientations of the Fe magnetization. We found {\Delta}I on the order of 5.9% for 100% circularly polarized light, both in the forward and the reverse bias, with a contribution of 0.8% from the Fe dichroic light absorption and of 5.1% from the spin filtering of photo-generated carriers crossing the Fe/MgO/Ge tunneling barrier.