Giant magnetoresistance: a primer

An introduction to the phenomenon of giant magnetoresistance is presented. It is pointed out that the giant magnetoresistance effect appears in a number of ultrathin multilayer systems in which thin magnetic films, a few tens of Å thick, are separated by nonmagnetic metal films, also on the order of tens of Å thick. For the effect to appear, the primary requirement is that the relative orientation of successive magnetic layers must be susceptible to change by the application of a magnetic field. The basic physical origin of the effect is the differential scattering of electrons parallel to and antiparallel to the local magnetization. This differential scattering arises either from the character of the scattering centers or in the different density of states functions for the two spin species. The giant magnetoresistive effect is of interest because of its potential utility in magnetoresistive read heads in the information storage industry