A magnetoelastic metallic glass low-frequency magnetometer

A complete theoretical analysis is presented of the operation of a magnetoelastic amorphous metal low-frequency magnetic field sensor. This directional magnetometer is a hybrid device consisting of a piezoelectric plate, a field-annealed amorphous metal ribbon, and a viscous fluid, and it exhibits a low-frequency magnetic field detection level of 8.0 pT/√Hz at 1.0 Hz. The sensor may also be configured as a first- and second-order gradiometer. The device analysis focuses on the influence of the constituent materials on the magnetometer performance, identifying potential noise sources and optimal design parameters. This analysis may be applied to a variety of magnetoelastic amorphous metal sensors, e.g. stress, strain, and torque sensors, and is also useful in research concerning fundamental aspects of magnetoelasticity. Experimental data are presented demonstrating the performance of magnetometers constructed with amorphous metal ribbons exhibiting striped and closure domain structures