Ferromagnetic resonant tunneling diodes as spin polarimeters and   polarizers
  A method for measuring the degree of spin polarization of magnetic materials based on spin-dependent resonant tunneling is proposed. The device we consider is a ballistic double-barrier resonant structure consisting of a ferromagnetic layer embedded between two insulating barriers. A simple procedure, based on a detailed analysis of the differential conductance, allows to accurately determine the polarization of the ferromagnet. The spin-filtering character of such a system is furthermore addressed. We show that a 100% spin selectivity can be achieved under appropriate conditions. This approach is believed to be well suited for the investigation of diluted magnetic semiconductor heterostructures. 
Francesco Giazotto (1), Fabio Taddei (1 and 2), Rosario Fazio (1), and   Fabio Beltram (1) ((1) NEST-INFM & Scuola Normale S...