Magnetic bistability applied to sensors based on demagnetizing processes

Abstract
Ferromagnetic amorphous ribbons with an helical anisotropy, that show bistable magnetization processes in which the magnetization in the center and in both surfaces are coupled have been recently reported. These special magnetization processes make these kind of samples suitable for their use as sensor cores of magnetometers based on "demagnetizing processes". If an alternating current of decreasing amplitude is applied through the sample, the central zone magnetization has the same probability of being in either axial directions at zero current and without any external magnetic field. However, if a weak magnetic field is applied in one of these directions, the central zone magnetization will be definitely in the field direction. We have developed an electronic device that demagnetizes the sample at a rate of 120 per second and meaures the magnetization in the axial direction when the current reaches zero amplitude. By averaging these values, a very sensitive magnetometer (1.2 V/µT) has been developed.