  In this paper, spin-dependent transport through a spin diode composed of a
quantum dot coupled to a normal metal and a ferromagnetic lead is studied. The
current polarization and the spin accumulation are analyzed using the equations
of motion method within the nonequilibrium Green's function formalism. We
present a suitable method for computing Green's function without carrying out
any self-consistent calculation. The influence of coupling strength and
magnetic field on the spin current is studied and observed that this device
cannot work as a spin diode under certain conditions.
