Semiclassical theory of spin-polarized shot noise in mesoscopic diffusive conductors

TL;DR

This paper develops a semiclassical theory to analyze spin-polarized shot noise in a three-terminal diffusive conductor, revealing how spin-flip scattering and terminal polarizations influence current fluctuations and enabling measurement of spin-flip rates.

Contribution

It introduces a semiclassical Boltzmann-Langevin framework for spin-dependent shot noise in multi-terminal systems with variable polarizations and spin-flip scattering.

Findings

Current fluctuations are significantly affected by spin-flip scattering.

Noise measurements can determine the spin-flip scattering rate.

The theory covers various magnetic configurations and polarization angles.

Abstract

We study fluctuations of spin-polarized currents in a three-terminal spin-valve system consisting of a diffusive normal metal wire connected by tunnel junctions to three ferromagnetic terminals. Based on a spin-dependent Boltzmann-Langevin equation, we develop a semiclassical theory of charge and spin currents and the correlations of the currents fluctuations. In the three terminal system, we show that current fluctuations are strongly affected by the spin-flip scattering in the normal metal and the spin polarizations of the terminals, which may point in different directions. We analyze the dependence of the shot noise and the cross-correlations on the spin-flip scattering rate in the full range of the spin polarizations and for different magnetic configurations. Our result demonstrate that noise measurements in multi-terminal devices allow to determine the spin-flip scattering rate by changing the polarizations of ferromagnetic terminals.