IMPROVEMENT IN HIGH-FREQUENCY MAGNETIC-PROPERTIES OF AMORPHOUS SCORESBY THIN SURFACE OXIDE LAYERS ON RIBBONS

A thin oxide layer with the effective thickness of about 150 nm was pr epared on a surface of a thin Co-based amorphous ribbon by acid-treatm ent followed by annealing, and magnetic properties of cores made of it were studied. The oxide layers increased electric resistance between the ribbons and improved high frequency magnetic properties of the cor es. For a core made of a 6.8-mu m-thick ribbon, the acid-treatment inc reased the real part of the complex permeability, mu', by 60% and decr eased tan delta/mu' (delta : the loss angle) by 48% at 10MHz. The magn etic loss at a large excitation level was also reduced by the treatmen t. The obtained improvement was more remarkable than that obtained pre viously for the cores made of the ribbon with silicone interlayer insu lation.