Magnetic Sensor Using Second Harmonic Change in Magneto-Impedance Effect

Abstract

This study reports on a magnetic sensor composed of a Cu wire sandwiched between Co-based amorphous ribbons. The impedance of the Cu wire largely depends on the permeability of the amorphous ribbons and changes with an external field. This phenomenon results in a change in the voltage at the fundamental frequency ( V 1st ) and that at the second harmonic frequency ( V 2nd ) at both ends of the Cu wire. The maximum V 2nd variation rate was ∼150%/Oe which is about 15 times larger than that of V 1st . The detection of the second harmonic voltage offers the potential for a great improvement in the magnetic field sensitivity.