Description of a thin film directional magnetometer

We describe a new type of directional magnetometer based on a novel process utilizing the hysteretic properties of a soft cylindrical ferromagnetic thin film having circumferential anisotropy. The physics on which the operation of our sensor is based deals with the rotation of the magnetization vector of a soft magnetic material under a selected working geometry of applied fields and provides the computation of the resulting "field-voltage" transfer function. The principal difficulties encountered during development work are discussed. The trickiest part was the preparation of the thin film itself. The essential steps of our best production process includes multiple vacuum evaporations to give a composite of several non-magnetostrictive Fe-Ni films separated by SiO films. Data representing the performance of our magnetometer are presented.