The Giant Magneto-impedance Characteristics Of Amorphous Wires Under The Non-axial Magnetic Field

The giant magneto-impedance(GMI)effect of amorphous wire is widely used in the detection of external magnetic field information in amorphous wire magnetic sensor.The existing modeling method and characteristic research of amorphous wire GMI effect are only limited to the axial magnetic field.In order to improve the resolving power of amorphous wire magnetic sensors in different directions,a GMI analysis method for non-axial magnetic fields is provided in this thesis.By analyzing the magnetic domain structure and magnetization mechanism of amorphous wire,The mechanism of the external magnetic field on the magneto-impedance of the amorphous wire was found,and the key factors influencing the giant magneto-impedance effect of the amorphous wire were discussed.The theoretical model of the complex impedance of amorphous wire under non-axial magnetic field is further constructed.By using the Maxwell equation and the Landau-Lifshitz equation,the approximate complex impedance expression of amorphous wire under high frequency and low frequency is given respectively.In addition,the numerical calculation method of giant magneto-impedance under non-axial magnetic field is proposed,The free energy of the amorphous wire is discretized by dividing the surface domain of the amorphous wire.The relationship between the complex impedance and the applied magnetic field under different conditions was obtained.Finally,the GMI effect of the amorphous wire under the non-axial magnetic field was analyzed by combining the theoretical model and the experimental data.The results show that the non-axial magnetic field has the same bimodal characteristics as the axial magnetic field,the maximum value of the impedance exists under a specific magnetic field,and the change of the impedance in the specific magnetic field range is remarkable.With the increase of the angle,the sensitivity of the amorphous wire to the external magnetic field decreases,and the impedance characteristic curve will shift to the high field,the axial magnetic field have the best GMI effect.