Spin diode in the ballistic regime

We propose a spin diode based on two semiconducting quantum wires coupled by a tunnel barrier. Applying a voltage and a magnetic field gradient between the two semiconductor wires, we obtain a spin current rectification device which operates in the ballistic regime. Using the scattering states formalism, we derive an exact analytic expression for the tunneling current. The characteristics $I(V,H)\mathrm{}$ of the spin diode are determined.