Giant magnetoimpedance in soft magnetic amorphous and nanocrystalline materials

Recent results on giant magnetoimpedance (GMI) are reviewed. After a brief outline on the existent theories which explain the phenomenon, a general overview of experimental data on amorphous wires and ribbons is given. Furthermore, the GMI effect is observed in soft magnetic crystalline and nanocrystalline samples, and few investigations done in different systems are presented. To conclude, a recently observed effect in amorphous materials, the so-called magnetoimpedance aftereffect, is reported and explained as a consequence of the relaxation of the circular magnetic permeability.