A low-noise single-domain fluxgate sensor

In order to gain a better understanding of the noise mechanisms and limitations of fluxgate magnetometers, fluxgates with single and multidomain tubular permalloy cores were fabricated and tested. Under similar excitation conditions, single-domain fluxgates show approximately two orders of magnitude better resolution than similarly sized multidomain fluxgates, indicating that domain wall motion is the mechanism that limits conventional multidomain fluxgate resolution. Noise in a single-domain fluxgate was shown to decrease to 10(-11) T-rms/root Hz as the drive and a superimposed circumferential magnetic field were increased. Results suggest that further noise reductions are possible. (C) 1996 American Institute of Physics.