Electric-Field-Dependent Spin Polarization in GdN Spin Filter Tunnel Junctions

Tunnel junctions incorporating GdN ferromagnetic semiconductor barriers show a spin polarization exceeding 90% and a high conductance. These devices show an unusual low-bias conductance peak arising from a strong bias-dependence of the spin polarization. This originates from a strong magneto-electric coupling within a double Schottky barrier formed with the NbN electrodes.