Enhancing linearity of open-loop parallel fluxgate sensors via induced anisotropy in amorphous wires

Fluxgate sensors with amorphous wires can meet stringent volume constraints in an open-loop configuration. However, achieving consistent linearity over a broad range remains a significant challenge. In this study, we demonstrate that the transverse anisotropy resulting from tensile stress annealing (TSA) helps reduce the second harmonic component in the induced signal and improves the magnetization stability of the amorphous wires under varying external magnetic fields. This enhancement is beneficial for improving the linearity of the open-loop parallel fluxgate sensor. Additionally, this study provides clarity on how TSA contributes to improved sensor linearity, by examining the relationships among TSA, permeability, AC/DC hysteresis profiles, and the dynamics of domain structures. Notably, the optimization of linearity through TSA is accompanied by a corresponding increase in sensor noise levels.