CHAPTER 3 – Spin-Injection Phenomena and Applications

Publisher Summary A direct current injected into a magnetic multilayer induces torque on the magnetic moments in the layer and results in the amplification of precessional motion and successive magnetization switching of the magnetic moments. These phenomena provide new techniques to write information into tiny magnetic cells and to construct oscillators and rectifiers that are several tens of nanometres in size. In this chapter, spin injections and spin torques in magnetic multilayers, which show giant magnetoresistance effect in current-perpendicular-to-the-plane (CPP-GMR) geometry, and magnetic tunneling junctions (MTJs) are described. The mechanisms of spin-injection magnetization switching (SIMS) and its high-speed observations are explained. The chapter also provides details of phenomena related to spin injection, namely, spin-transfer oscillation (STO), and the spin-torque diode effect. Furthermore, applications related to the spin-injection technology are reviewed.