This chapter discusses the effects of a spin current injected into a uniformly magnetized ferromagnetic cell. The junction consists of two ferromagnetic layers separated by a nonmagnetic metal interlayer or insulating barrier layer. With a nonmagnetic metal interlayer, the junction is called a giant magnetoresistive nanopillar, and with an insulating barrier layer a magnetic-tunnel junction. When charge current is passed through this device, the electrons are first spin polarized by the fixed layer and spin-polarized current is then injected into the free layer through the nonmagnetic interlayer. This spin current interacts with the spins in the host material by an exchange interaction and exerts a torque. If the exerted torque is large enough, magnetization in the free layer is reversed or continuous precession is excited.
Probing the role of the barrier layer in magnetic tunnel junction transport
