THE MAGNETIZATION REVERSAL PROCESS IN AMORPHOUS WIRES

The most outstanding property of amorphous wires is their capability to be largely magnetized through a single Barkhausen jump giving rise to squared hysteresis loop. This phenomenon is spontaneously shown in large magnetostriction wires in the as-quenched state. According to the previous model, such a Barkhausen jump arises from the magnetization reversal inside a core having axial easy magnetization axis. In this work, we review some recent results leading to a refinement of the previous model paying particular attention to the domain structure close to the ends of wires having different lengths. The existence of ''closure'' domains in such regions and their variation when applied fields up to a critical value for magnetization reversal is of primary importance for understanding the reversal process. To deepen the knowledge of the dynamics of the wall responsible for the magnetization reversal two experimental studies were performed namely, the conventional Sixtus-Tonks experiment and the magnetization reversal under homogeneous applied field along the sample. The main conclusions are: a) the reversal process is spontaneously initiated close to the end of the wire where the wall is depinned and propagates along the entire wire, b) the starting end alternates in each reversal or remains the same depending on an additional external applied field, and c) the wall during the reversal approaches a planar shape.