Highly sensitive magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire

Abstract

The design and performance of a magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire are presented. The sensing element of the magnetometer is a 10‐mm long piece of Co–Fe–Ni–B–Si–Mo microwire with a small pick‐up coil of 85 turns wounded around the microwire. The electronics with a feedback circuit is used to register an electromotive force proportional to the external magnetic field applied along the wire axis. In the absence of the feedback current the magnetometer is capable of measuring a narrow range of magnetic fields, ±3.5 μT, in the frequency range of 0–1 kHz, the level of the equivalent magnetic noise being about 10 pT Hz −1/2 at a frequency of 300 Hz. The use of the feedback circuit increases the range of the measured magnetic fields up to ±250 μT. Photo of the giant magnetoimpedance magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire.