Abstract

Spintronics is now an important field of research with major applications in several technologies. Its development has been triggered by the discovery [1,2] of the giant magnetoresistance (GMR) in 1988. The basic concept of spintronics is the manipulation of spin-polarized currents, in contrast to mainstream electronics in which the spin of the electron is ignored. Adding the spin degree of freedom provides new effects, new capabilities, and new functionalities. Spin-polarized currents can be generated by exploiting the influence of the spin on the transport properties of the electrons in ferromagnetic conductors. This influence, first suggested by Mott [3], had been experimentally demonstrated and theoretically described in early works [4,5] more than 10 years before the discovery of the GMR. The GMR was the first step on the road of the utilization of the spin degree of freedom in magnetic nanostructures. Its application to the read heads of hard discs greatly contributed to the fast rise in the density of stored information and led to the extension of the hard disk technology to consumer’s electronics. Then, the development of an intensive research revealed many other phenomena related to the control and manipulation of spin-polarized currents. Today, the field of spintronics is expanding considerably, with very promising new axes like the manipulation of magnetic moments and the generation of microwaves by spin transfer, spintronics with semiconductors, molecular spintronics, the spin Hall effect (SHE), the quantum spin Hall effect (QSHE), and single-electron spintronics for quantum computing. In this chapter, I will tell the story of this development from the early experiments on spin-dependent conduction in ferromagnets to the emerging directions of today.