Spin-induced charge correlations in transport through interacting quantum dots with ferromagnetic leads

TL;DR

This paper investigates how spin-induced charge correlations affect electronic transport in quantum dots with ferromagnetic leads, revealing super-Poissonian behavior and diverging cumulants near full polarization.

Contribution

It provides a detailed analysis of full counting statistics in quantum dots with ferromagnetic leads, highlighting the role of spin polarization and Coulomb interaction in transport fluctuations.

Findings

Super-Poissonian transport due to spin correlations

Positive cross correlations between spin currents

Diverging cumulants as spin polarization approaches unity

Abstract

We study the full counting statistics of electronic transport through a single-level quantum dot weakly coupled to two leads, with either one or both of them being ferromagnetic. The interplay of Coulomb interaction and finite spin polarization implies spin-correlation induced charge correlations that give rise to super-Poissonian transport behavior and positive cross correlations of the currents of the two spin species. In the case of two ferromagnetic leads, we analyze the nontrivial dependence of the cumulants on the angle between the polarization directions of the leads. We find diverging second and higher cumulants for spin polarizations approaching unity.