ABSTRACT
As discussed in previous chapters, an electric current in a magnetic multilayer is spin polarized and yields a torque exerted on a local spin momentum. Such an electric current-induced spin torque in magnetic multilayers was ¢rst predicted theoretically [1,2] and subsequently observed experimentally in metallic nano-junctions by excitation of spin waves [3] and spin injection magnetization switching (SIMS) [4,5]. že e¥ects of the spin torque was also claimed to be observed in a perovskite system [6]. Further, SIMS was also observed in magnetic tunnel junctions (MTJs) with an Al-O barrier [7] and an MgO barrier [8,9] and in magnetic semiconductor systems [10].
