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

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.