The Larmor clock and anomalous spin dephasing in silicon

TL;DR

This paper demonstrates that in silicon, spin diffusion and dephasing can be significantly enhanced compared to charge diffusion, challenging previous predictions of suppression due to Coulomb interactions, using the Larmor clock technique.

Contribution

It introduces a novel application of the Larmor clock to reveal enhanced spin dephasing in silicon, contrasting with existing theories of Coulomb-drag effects.

Findings

Spin dephasing is greatly enhanced in silicon.

Spin diffusion exceeds charge diffusion in certain conditions.

Contradicts previous predictions of Coulomb-drag suppression.

Abstract

Drift-diffusion theory - which fully describes charge transport in semiconductors - is also universally used to model transport of spin-polarized electrons in the presence of longitudinal electric fields. By transforming spin transit time into spin orientation with precession (a technique called the "Larmor clock") in current-sensing vertical-transport intrinsic Si devices, we show that spin diffusion (and concomitant spin dephasing) can be greatly enhanced with respect to charge diffusion, in direct contrast to predictions of spin Coulomb-drag diffusion suppression.