Spin-valve effects in nickel/silicon/nickel junctions

We report on fabrication and characterization of a planar spin-valve device which has two sets of interdigited nanoscale Ni fingers as two electrodes in Schottky contact with Si. The finger width is 75 nm for one set and 150 nm for the other. A large length-to-width ratio of the fingers results in a single domain magnetization and a sharp magneto-resistance (MR) response. The switching field of the finger is determined by the finger width and spacing due to magnetostatic interaction. MR measurements reveal spin-valve effects in the Ni/Si/Ni junctions with MR changes of 0.3-0.6% at room temperature. The effects are discussed within a spin-valve model.