Devices such as transistors, amplifiers, frequency multipliers, and
square-law detectors use injection of spin-polarized electrons from one
magnetic region, into another through a control region and spin
precession of injected electrons in a magnetic field induced by current
in a nanowire. In one configuration, the nanowire is also one of the
magnetic regions and the control region is a semiconductor region between
the magnetic nanowire and the other magnetic region. Alternatively, the
nanowire is insulated from the control region and the two separate
magnetic regions. The relative magnetizations of the magnetic regions can
be selected to achieve desired device properties. A first voltage applied
between one magnetic region and the other magnetic nanowire or region
causes injection of spin-polarized electrons through the control region,
and a second voltage applied between the ends of the nanowire causes a
current and a magnetic field that rotates electron spins to control
device conductivity.