  Two types of spintronic devices on the base of magnetic nanostructures
containing silicon dioxide films with cobalt nanoparticles SiO2(Co) on GaAs
substrate - magnetic sensors and field-effect transistor governed by applied
magnetic field - are studied. Magnetic sensors are based on the injection
magnetoresistance effect. This effect manifests itself in avalanche suppression
by the magnetic field in GaAs near the SiO2(Co)/GaAs interface. Field-effect
transistor contains the SiO2(Co) film under gate. It is found that the magnetic
field action leads to great changes in electron mobility in the channel due to
the interaction between spins of Co nanoparticles and electron spins.
