Spin-resolved bunching and noise characteristics in double quantum dots coupled to ferromagnetic electrodes

TL;DR

This paper investigates spin-resolved noise and bunching phenomena in double quantum dots with ferromagnetic electrodes, revealing new dynamical spin blockade mechanisms and their correlation effects.

Contribution

It introduces a novel dynamical spin $

$-$

$ blockade mechanism and explores coexistence of different spin bunching behaviors in quantum dot systems.

Findings

Identification of spin $

$-$

$ blockade mechanism

Correlation between opposite spin current fluctuations

Coexistence of different spin bunching regimes

Abstract

We study spin-resolved noise in Coulomb blockaded double quantum dots coupled to ferromagnetic electrodes. The modulation of the interdot coupling and spin polarization in the electrodes gives rise to an intriguing dynamical spin $\uparrow$-$\uparrow$ ($\downarrow$-$\downarrow$) blockade mechanism: Bunching of up (down) spins due to dynamical blockade of an up (down) spin. In contrast to the conventional dynamical spin $\uparrow$-$\downarrow$ bunching (bunching of up spins entailed by dynamical blockade of a down spin), this new bunching behavior is found to be intimately associated with the spin mutual-correlation, i.e., the noise fluctuation between opposite spin currents. We further demonstrate that the dynamical spin $\uparrow$-$\uparrow$ and $\uparrow$-$\downarrow$ bunching of tunneling events may be coexistent in the regime of weak interdot coupling and low spin polarization.