Coil-less fluxgate effect in amorphous wires

Abstract

In this study, the coil-less fluxgate properties of as-received amorphous microwires with the compositions (Co 0.94Fe 0.06) 72.5Si 12.5B 15, Fe 77.5Si 7.5B 15 and Co 72.5Si 12.5B 15 have been investigated. As its name implies, a coil-less fluxgate is a new type of magnetic field sensor without a coil. When the (Co 0.94Fe 0.06) 72.5Si 12.5B 15 wire is magnetically saturated in the circumferential direction with a 30 kHz and 48 mA driving current and under the effect of 33 π rad/m torsional strain, there is a linear variation in the second harmonic of the voltage from wire ends, U wire, as a function of the applied external dc magnetic field, H z, along the wire length. The slope of the second harmonic versus H z curve changes in opposite directions as the direction of torsional strain changes from the positive to the negative direction. Coil-less fluxgate effects in as-received Fe 77.5Si 7.5B 15 and Co 72.5Si 12.5B 15 wires have also been investigated. A very small change in the second harmonic of voltage U wire is observed in Fe 77.5Si 7.5B 15 wire, with some small hysteresis.