Elevated giant magneto-impedance in amorphous metallical co-dased alloys

This paper reviews results of an enhancement of giant magneto-impedance (GMI) in cobalt-rich amorphous glassy alloys. There are several ways of GMI increasing, namely: thermal, cryogenic and laser treatment. The results are explained via structural changes of ribbons surface and magnetio-optical properties. This phenomenon is interpreted via classical electromagnetic terms. The role of a conductive intermediate film in three-layer sandwich structures is also revealed. Such structure consisting of two cobalt-based ferromagnetic films and a conductive inner film of amorphous nickel shows significant increase of GMI ratio in comparison to a single layer. GMI enhancement makes possible to create new types of high sensitive magnetic field sensors. The investigation of evaluation processes after the ribbons treatment substantiates to clear understanding the nature of GMI.