Spin-dependent transport in a double barrier structure with a ferromagnetic material emitter

The differential conductance for a double barrier resonant tunnel diode is calculated by a recursive Green-function method based on the Keldysh formalism. The calculated results show that the conductance is strongly spin dependent for only the case where a positive bias voltage is applied between two barriers. The life time broadening at the Fermi level due to the magnetic impurity is found to be important to understand the dip structure of the conductance curve in experimental results. The features of the splitting of the dips in the calculated results are consistent with those in the experimental results.