SpinFETs

SpinFETs are transistor devices in which electron spin, rather than charge alone, is used to modulate conductance. The most studied variant is the Datta–Das spin field-effect transistor, proposed in 1990, in which spin-polarized current is controlled by gate-tunable spin precession in a semiconductor channel.

The operating principle relies on injecting a spin-polarized current from a ferromagnetic source into a semiconductor channel. As electrons traverse the channel, their spins precess around an effective magnetic field created by Rashba spin-orbit coupling, which can be adjusted with an electric gate. At the drain, the current depends on the projection of the spin onto the drain magnetization; by changing the gate voltage, the precession angle changes, modulating current and enabling an on/off behavior.

A typical device consists of ferromagnetic source and drain electrodes, a semiconductor or two-dimensional channel, and a gate to tune spin-orbit coupling. Candidate materials include III-V semiconductors such as InAs and GaAs, silicon with ferromagnetic contacts, and emerging platforms like graphene or topological insulators with proximity-induced magnetism. All-electric spin-FET concepts that rely solely on spin-orbit effects without magnetic electrodes have also been explored.

Despite progress, significant challenges remain. Experimental demonstrations of efficient spin injection, long spin coherence lengths at room temperature, and reliable, scalable fabrication are ongoing hurdles. Issues such as spin relaxation, impedance mismatch, and device variability impact performance and reproducibility.

SpinFETs offer potential advantages for low-power logic and reconfigurable computation, complementing conventional electronics. Realizing practical devices requires robust room-temperature operation, consistent fabrication, and seamless CMOS integration.