Coexistence of super-Poissonian mechanisms in quantum dots with ferromagnetic leads

Abstract

Spin-resolved noise correlations of electronic currents are investigated through a Coulomb-blockaded two-level quantum dot coupled to two ferromagnetic leads. By changing the bias voltage and/or modulating the spin polarization of leads, different types of dynamical mechanisms are formed to exhibit a sub- to super-Poissonian statistics crossover. An optimized electron correlation is obtained in the specifical regime where several dynamical mechanisms of electron bunching are coexistent. It is found that the shot noise spectrum of spin currents can act as a signal for differentiating which mechanism is responsible for the charge super-Poissonian transport statistics. In addition, the positive cross correlation for two spin species is also predicted.