An evaluation of the noise performance of Fe, Co, Si, and B amorphous alloys in ring-core fluxgate magnetometers

The work described herein has addressed two questions. Can amorphous metal alloys be used as core material for high-performance fluxgate magnetometers, and do these alloys provide a means for further understanding the noise mechanism(s) of fluxgate magnetometers?We have prepared and studied a suite of fourteen alloys of content (Fe, Co)70, (Si, B)30. Noise levels of the as-cast alloys correlate with coercivity and hysteresis losses and have a local minimum at zero magnetostriction. However, our overall noise minimum coincides with the minimum measured core losses—not at zero magnetostriction.Our best cores perform favourably when compared with the best commercially available Permalloy cores and outperform all cores of the same dimensions that we have examined. Thus we are able to conclude that amorphous metal alloys are a likely source of high-quality material for fluxgate magnetometers.