Gate control of a spin transistor via spin-orbit “focusing” of electron beams

Current proposals and implementations of spin field effect transistors (spin-FETs) rely on three key elements: (1) spin injection of highly spin polarized distribution into a channel, (2) gate control of the spin orientation or polarization in some fashion within the channel, and (3) sensitivity of current through a drain contact to spin polarization in the channel. Although all three of these effects have been demonstrated experimentally to some degree, elements (1) and (3) are still well below the required performance to yield a competitive device. Here we describe a new approach to gate-controlled electronic transport in a twodimensional electron gas, which relies on gate control of the spin-orbit interaction to control the direction and focusing of "electron beams" which propagate along specific crystal axes. A major advantage of this approach is that the electron beams exist even when the propagating electrons are not spin-polarized when injected. Thus no spin-selective injection or detection is required for this device, nor any magnetic materials or applied magnetic fields, only gatecontrol of the spin-orbit interaction.