Spin-filter transistor

We propose and theoretically analyze a spin-filter transistor (SIFT) employing the spin-filter effect in a ferromagnetic barrier layer. The proposed SFT has a tunneling-injection-type hot-electron-transistor structure with a thin ferromagnetic emitter barrier and a thick ferromagnetic collector barrier. The emitter barrier acts as a tunneling injector of highly spin-polarized hot electrons from the nonmagnetic emitter to the nonmagnetic base, and the collector barrier acts as a spin analyzer that determines the flow of spin-polarized hot electrons from the base to the nonmagnetic collector or to the base electrode. By the combination of these two spin filters, the output characteristics of the SIFT depend on the magnetization configuration (parallel or antiparallel) of the emitter and collector barriers. The SFT can realize not only a very large magnetocurrent ratio, but also current and power gains.