Journal of Physical Chemistry A, Vol.119, No.41, 10399-10407, 2015
Shot Noise of Charge and Spin Current of a Quantum Dot Coupled to Semiconductor Electrodes
On the basis of the scattering matrix theory and nonequilibrium green function method, we have investigated the fluctuations of charge and spin current of the systems that consist of a quantum dot (QD) with a resonant level coupled to two semiconductor contacts within in alternative site (AS) and alternative bond (AB) framework, where two transverse (B-x) and longitudinal (B-z) magnetic fields are applied to the QD. It is only necessary to use the auto-correlation function to characterize the fluctuations of charge current for a two-terminal system because of the relation that is defined as Sigma S-e(alpha)alpha beta = Sigma S-e(beta)alpha beta = 0. Our that result shows at both auto-shot noise (S-LL) and cross-shot noise (S-LR) are essential to characterize the fluctuations of spin current when Bx is present. Moreover, our model calculations show that the sign of the cross-shot noise of spin current is negative for all surface states of AS/QD/AS junctions, whereas it oscillates between positive and negative values for two surface states of AB/QD/AB junctions as we sweep the gate voltage.