Formalism to Optimize Magnetic Noise in Giant Magnetoimpedance-Based Devices

This paper describes a theoretical study of the sensitivity and intrinsic noise response in a longitudinal giant magnetoimpedance sensor of a magnetically soft microwire. We show that the ratio of the intrinsic magnetic noise voltage spectral density to the sensitivity is proportional to epsiv/sinthetas, where epsiv depends upon the internal field and frequency and thetas is the angle between the equilibrium magnetization and the axial applied static field. The model allows us to calculate the influence of the easy axis angle and the applied fields on sensor response and to obtain a working point. We show the conditions necessary to reduce the intrinsic noise level to the fT/radicHz level