The bipolar spin transistor. A novel solid state device taking its first steps

The spin transistor is a trilayer, three terminal device similar in some ways to a semiconductor bipolar transistor. Although the physical principles of operation are different, the language of semiconductor physics is borrowed to facilitate the description. The emitter and collector layers of the spin transistor are ferromagnetic films characterized by a magnetization that lies in the plane of the films and has an externally manipulated direction. The base layer is a nonmagnetic metal, such as gold, copper or silver. One could fabricate an array of elements as a nonvolatile random access memory (NRAM). The magnetization orientation of all the emitter films is initially set by application (and subsequent removal) of a large magnetic field. The magnetization of the collector films is manipulated by sending currents through an over-layed array of write wires