Giant Magnetoresistance (GMR)

Abstract

In this chapter, we have introduced and discussed the concept of Giant Magnetoresistance (GMR). As a prelude, Ordinary Magnetoresistance, i.e., magnetoresistance of ferromagnetic transition metals and Anisotropic magnetoresistance of ferromagnetic transition metals have been discussed. Different kinds of GMR, such as multilayer GMR, spin-valve GMR, pseudo-spin-valve GMR, and granular GMR, have also been reviewed briefly. We have presented an elaborate explanation of the Physical Origin of GMR. In this direction, spin-dependent and spin-flip scattering of electrons in Multilayers have been considered. We have also presented an explanation of the negative magnetoresistance of ferromagnetic transition metals, considering spin-scattering mechanisms. We have explained qualitatively how the Mott model could describe GMR. A quantitative explanation has also been given here. Magnetoresistance theory, based on Resistor Network Theory of GMR, has been discussed. Furthermore, Periodic Superlattice Structure has also been highlighted. Most currently available commercial spintronics products, such as magnetic read heads for reading data in computer hard disks and magnetic random access memory, are based on a giant magnetoresistance effect.