Spin and Charge Shot Noise in Mesoscopic Spin Hall Systems

TL;DR

This paper investigates the shot noise in mesoscopic spin Hall systems, revealing how noise measurements can distinguish between intrinsic and extrinsic spin-orbit mechanisms affecting spin and charge currents.

Contribution

It introduces a scattering approach to analyze shot noise in multiterminal spin Hall systems, providing a new method to differentiate spin-orbit mechanisms via noise characteristics.

Findings

Shot noise can distinguish between intrinsic and extrinsic spin-orbit effects.

Spin-flip processes significantly contribute to shot noise levels.

Noise analysis offers a tool to identify the underlying spin Hall mechanisms.

Abstract

Injection of unpolarized charge current through the longitudinal leads of a four-terminal two-dimensional electron gas with the Rashba spin-orbit (SO) coupling and/or SO scattering off extrinsic impurities is responsible not only for the pure spin Hall current in the transverse leads, but also for random time-dependent current fluctuations. We employ the scattering approach to current-current correlations in multiterminal nanoscale conductors to analyze the shot noise of transverse pure spin Hall and zero charge current, or transverse spin current and non-zero charge Hall current, driven by unpolarized or spin-polarized longitudinal current, respectively. Since any spin-flip acts as an additional source of noise, we argue that these shot noises offer a unique tool to differentiate between intrinsic and extrinsic SO mechanisms underlying the spin Hall effect in paramagnetic devices.