Positive current noise cross-correlations in capacitively coupled double quantum dots with ferromagnetic leads

TL;DR

This study investigates current cross-correlations in double quantum dots with ferromagnetic leads, revealing spin-dependent effects that can reverse or enhance correlations, differing from paramagnetic cases.

Contribution

It introduces a new mechanism of dynamical spin blockade affecting current correlations in ferromagnetic quantum dot systems.

Findings

Positive current cross-correlations can be achieved with ferromagnetic leads.

Spin-dependent bunching influences current correlations.

Sign-reversal of correlations occurs in dynamical channel blockade regimes.

Abstract

We examine cross-correlations (CCs) in the tunneling currents through two parallel interacting quantum dots coupled to four independent ferromagnetic electrodes. We find that when either one of the two circuits is in the parallel configuration with sufficiently strong polarization strength, a new mechanism of dynamical spin blockade, i.e., a spin-dependent bunching of tunneling events, governs transport through the system together with the inter-dot Coulomb interaction, leading to a sign-reversal of the zero-frequency current CC in the dynamical channel blockade regime, and to enhancement of positive current CC in the dynamical channel anti-blockade regimes, in contrast to the corresponding results for the case of paramagnetic leads.