Influence of magnetization processes and device geometry on the GMI effect

Summary form only given. The use of Giant Magneto-Impedance as a mechanism for sensor design has been stressed in the past few years. Nowadays, some devices are already in the market and many different materials with various shapes have been tested for these sensors. In this paper we review the different geometries (wires, ribbons, films) and structures (either homostructures or sandwiches and plated wires) as well as the different materials (either amorphous or crystalline) and magnetization processes occurring in the GMI elements. The different character of the magnetic anisotropy in crystalline and amorphous alloys determines the type of magnetization process dominant in the material (either wall movement or magnetization rotation) as well as the single peak or double peak behaviour of the GMI. The wall movement results typically in larger permeability values and then in improved GMI ratios. However the damping of the walls rapidly reduces the effective permeability that becomes the one corresponding to that of rotation processes.