Correlation of magnetic and structural properties of glass-coated Cu-based microwires

The microstructural characteristics of Cu-based glass coated microwires (Cu70Fe30 and Cu80Co20) are studied considering their composition and geometry determined by their fabrication. The parameter describing the geometry is the ratio ρ between the diameter of the metallic nucleus and the external one of the layer of the Pyrex glass. αFe and Co phases (nanocrystals of some 40 nm) coexist with a Cu phase in each system. The relative content of each phase shows a non-linear ρ-dependence with a critical maximum at around ρ=0.2 for the αFe and Co phases. Hysteresis measurements show that the ratio ρ is also critical in the magnetic characterization of the microwires