Shot noise of spin current

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.