Exchange-driven magnetoresistance in silicon facilitated by electrical spin injection

TL;DR

This paper demonstrates how electrical spin injection can reveal exchange interactions in phosphorus-doped silicon through a magnetoresistance effect, showing a Lorentzian signal at low temperatures caused by spin-dependent scattering.

Contribution

It introduces a novel method to detect exchange interactions in silicon using electrical spin injection and analyzes a unique low-temperature Lorentzian signal.

Findings

Exchange interactions can be probed via magnetoresistance in Si:P.

A Lorentzian-shaped signal appears at low temperatures.

The signal results from spin-dependent scattering, not spin relaxation.

Abstract

We use electrical spin injection to probe exchange interactions in phosphorus doped silicon (Si:P). The detection is enabled by a magnetoresistance effect that demonstrates the efficiency of exchange in imprinting spin information from the magnetic lead onto the localized moments in the Si:P region. A unique Lorentzian-shaped signal existing only at low temperatures ($\lesssim 25 K$) is observed experimentally and analyzed theoretically in electrical Hanle effect measurement. It stems from spin-dependent scattering of electrons by neutral impurities in Si:P. The shape of this signal is not directly related to spin relaxation but to exchange interaction between spin-polarized electrons that are localized on adjacent impurities.