Observation of spin filtering in magnetic insulator contacts to silicon

The magnetic insulator EuS is used to create a spin-selective and conductivity-matched tunnel contact to silicon, in analogy to a conventional ferromagnetic metal/semiconductor configuration employed for spin injection. The spin filter efficiency of such a magnetic “spin filter” tunnel barrier is quantified using an adjacent Co ferromagneticelectrode as spin detector in a spin valve-type structure. This previously unobserved magnetoresistance effect demonstrates the efficient spin-polarizing nature of magnetic semiconductors on silicon and its prospective functionality as spin injectors/detectors in hybrid semiconductor devices