A semiconductor field-effect transistor in which the normal metal pads, such as Cu, are replaced with magnetic metal pads, such as Fe, so that the device will work on the electron spin principle. The magnetic pads, where the densities of states at the Fermi level are different for spin up and spin down channels, are used to preferentially inject and detect specific spin orientations. A spin-orbit interaction in the two-dimensional electron gas causes the spin to precess, so the spin direction can be modulated by the gate voltage. The current of the spin FET can then be controlled by changing the spin direction with respect to that of the analyser electrode. The spin FET is fast and may be operated for both data storage and processing. See spintronics.