Estudo dos processos de magnetização em microfios amorfos recobertos por vidro sob efeito de tensões mecânicas

Abstract

The study of the magnetization dynamics in amorphous microwires has attracted an increasing interest in the last two decades mainly due to its magnetic behavior characterized by a single and large Barkhausen jump, a feature of a squared magnetization curve. A complete comprehension of the magnetic properties in these microwires is relevant due both, the potential of application in magnetic sensors and understanding the physics behind the phenomenon. The main objective of this work is to study the magnetization processes in amorphous glass covered microwires (AGCW), nominal composition Co 68 , 25 Fe 4 , 5 Si 12 , 25 B 15 , diameter of 44 m and metallic nucleus of 17 m, produced by the Taylor-Ulitovski method, when submitted to different values of mechanical stress. The production method consists in the rapid drawing of a softened glass capillary which the molten metal is entrapped. The cooling of the material in the amorphous phase induces a strong internal stress. By the application of external mechanical stress, the internal stress configuration is modifcated resulting in the change of the microwire magnetic anisotropy. The evolution of the magnetic structure is analysed starting from the modifications observed in the shape of the magnetization curves, when the sample is submitted to different mechanical stress.