Current and Shot Noise in a Quantum Dot Coupled to Ferromagnetic Leads   in the Large U Limit
  Using the Keldysh nonequilibrium Green function technique, we study the current and shot noise spectroscopy of a single interacting quantum dot coupled to two ferromagnetic leads with different polarizations. The polarizations of leads can be both parallel and antiparallel alignments. General formulas of current and shot noise are obtained, which can be applied in both the parallel and antiparallel alignment cases. We show that for large polarization value, the differential conductance and shot noise are completely diferent for spin up and spin down configurations in the parallel alignment case. However, the differential conductance and shot noise have the similar properties for parallel alignment case in the small polarization value and for antiparallel alignment case in any polarization value. 
Rong Lu and Zhi-Rong Liu