Highly Sensitive GMI Sensor with an Equivalent Noise 0.3 nT

This paper is devoted to a highly sensitive GMI sensor, up to 0.3 nT, at low magnetic field. Sine wave with high frequency is selected as the ac current excitation to the amorphous wire, because it has the largest output signal among sine wave, pulse wave and triangular wave. The thermal magnetic fluctuation, which determines the sensitivity limit, is suppressed by current treating the amorphous wire before use. The circuit and the bias magnetic field are powered by a constant voltage from a classical GIC. With a fairly good V. In a?linear ration, the output is 25 mV / 1000 nT, and the noise is 8 comparison mode, the magnetic field as low as 0.2 nT is detectable. The sensor performs well in a reasonable temperature span of about 80 K around the room temperature.