Mechanism of Matteucci Effect Using Amorphous Magnetic Wires

The mechanism of the sensitive Matteucci effect in negative-magnetostrictive amorphous wires was qualitatively clarified by considering a magnetic domain model and using measurements of BH hysteresis loops for circular magnetization. Three kinds of amorphous wires, FeSiB, CoSiB and FeCo-SiB, with diameters of 50 m and 120 m, were investigated. It was found that the Matteucci voltage was determined by the differential permeability of the BH hysteresis loops, which was highest for FeCoSiB wire with a small negative magnetostriction (λ
_s
=0.1×10
^-6
). Variations in the Matteucci voltage with tension and sample annealing are also explained in terms of the BH characteristics. Three kinds of Matteucci effect were identified, occurring for the cases of (i) an ac wire current, (ii) a perpendicular ac magnetic field, and (iii) a high-frequency wire current and a low-frequency perpendicular ac magnetic field. These effects are the basis of a new data tablet and new rotary encoder.