In the last decade after the discovery of giant magnetoresistance effects in me tallic
multilayers worldwide developments in basic research and in engineering applications have been
achieved and various remarkable results have been ob tained in both fields. On the basic
research into the GMR effects an excellent re view book edited by Hartmann was published in
1999 entitled Magnetic Multi layers and Giant Magnetoresistance and it describes the
experimental and theoretical aspects of GMR studies and the magneto-optics in metallic
multilayers including applications in electronic data storage fields. This book aims to give
an overview on the electronics applications of the GMR in metallic multilayers espe cially on
the sensors and memories in magnetic data storage the main concerns of electronic engineers.
If the mean free path of conduction electrons is longer than the period of the multilayer and
for a low applied magnetic field magnetizations in the adjacent magnetic layers are in
antiparallel the GMR effect in magnetic metallic multilay ers occurs due to the resistance
change in the electric current flowing in the layer plain with a change in the magnetization
from antiparallel to parallel alignment by an applied magnetic field (CIP mode) i. e. in the
saturation field magnetiza tions are in parallel and the resistance is lowered. The saturation
field H is given by the RKKY-like magnetic coupling between adjacent magnetic layers through a
nonmagnetic conductive layer between the layers.
