Dynamic spin-polarized shot noise in a quantum dot coupled to ferromagnetic terminals under the perturbation of ac fields

摘要

We have investigated the shot noise in the mesoscopic system composed of a quantum dot (QD) coupled to ferromagnetic terminals under the perturbation of ac fields. The shot noise has been derived using the nonequilibrium Green's function (NGF) technique to describe the spin polarization effect along with photon absorption and emission processes in the Coulomb blockade regime. We have examined the influence of spin polarization on the shot noise under the perturbation of ac fields in the nonadiabatic regime. The Coulomb blockade effect results in the modification of shot noise compared with the noninteracting case. The spin orientation contributes a spin valve effect for controlling electron tunnelling through this QD, and different resonant forms appear around the Coulomb blockade channel. The photon-assisted spin-splitting and spin-polarization effect contributes a photon-assisted spin valve to adjust the electron tunnelling current and shot noise. The spin-polarization effect varies the value of the Fano factor. However, it does not change the noise type from sub-Poissonian to super-Poissonian.