spinFET

A spinFET, short for spin field-effect transistor, is a device that uses the electron spin degree of freedom to influence electronic conduction. In the prototypical concept, a spinFET comprises a nonmagnetic semiconductor channel with ferromagnetic source and drain contacts that inject and detect spin-polarized electrons. The key idea is that the spin of electrons precesses as they travel through the channel, and this precession can be controlled by an electric field applied via a gate.

The operating principle originates from the Datta–Das transistor idea: spin-polarized electrons injected from the source enter a channel where spin precession is driven by spin–orbit interactions, such as the Rashba effect. The gate voltage modulates the strength of this spin–orbit interaction, thereby adjusting the precession rate. When the spins reach the drain, the detected current depends on the relative alignment of the electron spins with the drain’s magnetization, leading to a gate-tunable conductance. The resulting on/off behavior relies on maintaining spin coherence during transit and achieving efficient spin injection and detection.

Materials and implementations for spinFETs typically involve III–V semiconductor channels such as InAs or InGaAs, with ferromagnetic contacts or half-metallic electrodes. Challenges include achieving robust spin injection and detection, long spin lifetimes and coherence, and minimizing contact resistance and scattering that dampen spin signals. Practical devices have demonstrated spin-precession effects and some gate-tunable conductance modulation, but a scalable, high-contrast spinFET remains an area of active research.

Potential applications include spin-based logic, nonvolatile memory, and low-power electronics, where control of spin could complement or surpass charge-based operation.