Output Properties of Zero-Speed Sensors Using FeCoV Wire and NiFe/CoFe Multilayer Thin Film

Output properties of magnetic sensors generating pulse voltages are described. The sensors principally consisted of double magnetic layers with different coercive forces. Both of thin-film-based material and wire-based material were used for the double layers. When the magnetization of one of the layers was switched by an external magnetic field, a pulse voltage was induced in a pickup-coil wound around the materials. The magnetic sensor using a twisted FeCoV wire, the conventional material for the Wiegand effect, had the disadvantage of the asymmetric output voltage generated by the alternative magnetic field. It was found that a magnetic wire, whose ends were slightly etched, exhibited symmetric output voltage. The sensor element consisting of a patterned NiFe/CoFe multilayer thin film was also studied. Constant output voltage was obtained from this thin-film sensor using an excitation magnetic field at frequencies down to 0.1 Hz