Coil-less fluxgate effect in amorphous wires

In this study, the coil-less fluxgate properties of as-received amorphous microwires with the compositions (Co(0.94)Fe(0.06))(72.5)Si(12.5)B(15), Fe(77.5)Si(7.5)B(15) and Co(72.5)Si(12.5)B(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(0.94)Fe(0.06))(72.5)Si(12.5)B(15) wire is magnetically saturated in the circumferential direction with a 30 kHz and 48 mA driving current and under the effect of 33 pi 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(77.5)Si(7.5)B(15) and Co(72.5)Si(12.5)B(15) wires have also been investigated. A very small change in the second harmonic of voltage U(wire) is observed in Fe(77.5)Si(7.5)B(15) wire, with some small hysteresis. (C) 2010 Elsevier B.V. All rights reserved.