Effect of Field Annealing Induced Magnetic Anisotropy on the Performance of Meander‐Core Orthogonal Fluxgate Sensor

Abstract

The magnetic anisotropy field distribution is discussed for Co‐based amorphous ribbon annealed under different field conditions leading to different induced anisotropies: longitudinal field (LF) and transversal field (TF) annealing. In order to understand the relation between the field annealing‐induced anisotropy and the performance of meander‐core orthogonal fluxgate sensor, field‐annealed ribbons with different in‐plane anisotropies as cores of orthogonal fluxgate sensors are employed and both noise and sensitivity in fundamental mode are measured. Experimental results indicate that LF annealing‐induced anisotropy with easy axis perpendicular to the direction of excitation field can effectively improve the sensor sensitivity. On the other hand, TF annealing‐induced anisotropy with easy axis parallel to excitation field results in lower sensitivity, but the noise is also lower. The results obtained are useful for developing the high‐performance orthogonal fluxgate sensors based on amorphous ribbon cores.

Improved Performance of Fundamental Mode Orthogonal Fluxgate Using a Micro-Patterned Meander-Shaped Ribbon Core

“…It is noted that in the fundamental mode, the sensitivity is also dependent on the dc bias, which is much larger than the amplitude of ac current. For a given ac current, the sensitivity drops as the dc bias current increases [27]. Moreover, the choice of dc bias will affect the noise of the sensor.…”

Novel Giant Magnetoimpedance Magnetic Field Sensor

“…The 625 mA current annealed sample achieved a greater GMI impedance change ratio (according to Equation (1)) of 299.6%, but also had a greater anisotropy field value of 65.9 A/m. Annealing in the presence of a magnetic field (current flow through the annealed material by the Joule method, resulting in the creation of a transverse field to the direction of current flow) was shown in [50] to improve the noise properties of the material. High-resolution material testing also showed the exact shape of the impedance curve in the range (−Hk, +Hk).…”