Artificial magnetic superlattices

One of the predominant trends in solid state physics over the last decade has been the study of artificial materials which have been designed at the atomic level. These materials are produced using a variety of advanced deposition techniques, and range in scale from the sub-mono-layer, through thin films and up to superlattices. In the field of magnetism it is probably this last category of material that has attracted most recent interest, as magnetic superlattices display many unusual properties not found in the bulk state. For example, it has been discovered that the electrical resistance of certain superlattices formed from transition metals is reduced by a factor of 2 or more in a modest applied magnetic field [1]. By contrast, the resistance of a typical metal changes by only a few percent over the same range of applied field. This so-called giant mag-neto-resistance is now being exploited to produce more sensitive pick-up heads in the latest generation of high-density computer disks, even before theorists have settled their arguments about the precise origin of the mechanism.