A Domain Dynamic Model Study of Magneto-impedance Sensor in the Presence of Inhomogeneous Magnetic Fields

Abstract

We investigate the effect of an inhomogeneous external magnetic field and magnetization on magneto-impedance (MI) effect based on the domain dynamic model. The impedance (Z) of a thin magnetic layer under different field inhomogeneity and magnetization inhomogeneity (FIH/MIH) profiles is calculated. The MI effect determined in different frequencies shows fixed MI peak location when field and magnetization are homogeneous. However, for the cases of FIH/MIH conditions, the locations of the peaks are changed for different frequencies and layer thicknesses. The MI peaks are broadened due to the FIH profile since not all domains rotate uniformly as the field changes along the length of the layer. In the case of MIH, the values of impedance are decreased more than those of FIH (maximally about 8% at peak positions), and the MI peak positions have less shifted to higher field values (maximally about 25%) in comparison with the FIH peak positions. In the case of FIH and MIH, our calculations show the maximum relative change in the impedance peak position of about 12%. The obtained results present useful information for improving the performance of future magnetic sensors which work based on the MI effect.