Shot noise of spin current

TL;DR

This paper provides an exact analysis of the shot noise spectrum in a spin field effect transistor, revealing how spin and charge current fluctuations depend on device coupling and operational regime.

Contribution

It offers the first exact solution for spin-current noise spectrum in SFETs, including auto- and cross-correlation functions and charge-current shot noise.

Findings

Auto- and cross-correlation functions are essential for characterizing spin-current noise.

Charge-current shot noise exists even with zero net charge flow.

Noise spectra vary with coupling strength and differ between spin and charge currents.

Abstract

We report an exact solution for the noise spectrum of spin-current without charge-current in a spin field effect transistor (SFET). For the SFET with two leads, it is found that both auto- and cross-correlation functions are needed to characterize the noise of spin-current. A shot noise is also generated for the charge-current even though the net charge-current is identically zero. The noise spectra of spin-current and charge-current depends on the coupling strength between the SFET and the leads, and they may behave qualitatively differently. We also present results of noise spectra in the adiabatic regime.