MAGNETIC-PROPERTIES OF GLASS-COATED AMORPHOUS AND NANOCRYSTALLINE MICROWIRES

The magnetic properties of Fe- and Go-based amorphous and nanocrystall ine glass-coated microwires are reviewed. Such wires are composed of a metallic amorphous nucleus (3 to 20 mu m diameter) and an insulating glass cover (2 to 12 mu m thick). Interest is mainly focused on sample s exhibiting squared hysteresis loops (magnetically bistable) which ex hibit positive magnetostriction (bistability can be observed for 2 mm long samples). The internal stresses are much stronger than for in-rot ating-water quenched amorphous wires as a consequence of the presence of the glass coating and, coupled with magnetostriction, give rise to strong magnetoelastic anisotropies determining the magnetization proce ss. Upon heating, the structure evolves to nanocrystalline and microcr ystalline and although the magnetic behavior remains bistable a large influence on the switching field is observed (variations of switching field between 0.3 and 100 Oe). These magnetic properties make such mic rowires very promising for technological applications.