Orthogonal fluxgate sensor noise depends on annealing-induced magnetostriction of the core

Abstract

For long time amorphous microwires with (Co94Fe6)72.5Si12.5B15 composition have been extensively used for magnetic sensors, such as fluxgates but also magnetoimpedance, due to their vanishing magnetostriction. In fluxgate sensors we want to minimize the magnetostriction because it couples any mechanical stress (for instance due to thermal expansion) to the magnetic characteristic of the wire making the noise of the fluxgate sensor rise. In this paper we compared two magnetic wires, one with slightly negative and one with slightly positive magnetostriction in their as cast state and we anneal them measuring then how the magnetostriction and the noise evolves as we increase the annealing time.