Ferromagnet–semiconductor device with tunable tunnel characteristics

Abstract

A device is proposed consisting of a GaAs/AlxGa1−xAs heterostructure with a ferromagnetic strip placed on top that has an easy axis of magnetization perpendicular to the underlying two-dimensional electron gas. In addition, the strip is gated to form a combined magnetostatic and electrostatic barrier for the conduction electrons. On the basis of a simple model, which is of the Landauer–Büttiker type, such a structure is shown to have three different regimes of operation. Whereas for a certain regime, electrons can move according to the classical diamagnetic motion, there is also the possibility of tuning the device between nonresonant and resonant tunneling behavior. In the latter case the combined magnetostatic and electrostatic barrier acts as an energy and momentum filter. The proposed device could find application in digital logic circuits as an electromagnetic field-effect transistor.