Magnetic Thin Films and Multilayers

Abstract

Progress in high vacuum and ultra high vacuum material preparation techniques now allow the preparation of artificial structures consisting of ultra thin films of magnetic materials, as well as multilayer systems containing stacks of different materials, some of which being magnetic. In addition, many techniques are also now available for both the structural and magnetic characterization of these systems.The thickness of the individual layers may vary from one atomic plane to some tens of nanometres. These thicknesses are comparable to some characteristic length scales in magnetism: the Fermi wavelength, the range of exchange interactions, the domain wall thickness, the mean free path of electrons ...In general, magnetism is very sensitive to the local atomic environment. As it is possible to vary this environment in a very controlled way in thin films and multilayers, unique phenomena, which do not exist in bulk materials, can be observed in these systems.These phenomena include the possibility to stabilise new crystallographic phases, non-existent or very unstable in bulk form, the appearance of magnetic anisotropy induced by interfacial stress, magnetic coupling effects between adjacent films, giant magneto resistance, tunnel magnetoresistance.Apartfrom their interestfrom a fundamental point of view, thin films and multi/ayers find many applications, particularly in the area of magnetic or magneto-optical recording. These include media for both parallel and perpendicular magnetic recording, mediafor magneto-optical recording, soft magnetic thin films (flux guides, transformers ... ), magnetostrictive materials (microactuators), and magnetoresistive materials for magnetic field sensors.