Studies On Giant Magneto-impedance Effect And Magnetization Properties In FeCuNbSiB Multilayered Films

Due to the significant application perspective in the giant magneto-impedance (GMI) effect devices of film materials which are prone to integration and micromation, we have prepared FeCuNbSiB/SiO₂/Cu/SiO₂/FeCuNbSiB/SiO₂ multilayer films by magnetron sputtering method. By the methods of X-ray diffraction spectrums, surface magneto-optic Kerr effect and permeability spectrums, the changes of the samples' magnetic properties and GMI effect upon different sputtering powers and annealing temperatures are studied.1. With the increase of the sputtering power of magnetic layers, the plane coercive force of the samples decreased, which enhanced the soft magnetic properties and GMI effect. The sample deposited by sputtering power of 150W had the maximal GMI effect, 53% and 44.3% in transverse and longitudinal MI effect respectively. However, when the sputtering power reached 200W, the increasing sputtering stress induced the perpendicular anisotropy in the sample, thus reduced remarkably GMI effect of the material.2. The magnetic properties of the samples were strongly affected by annealing temperatures. The polar Kerr hysteresis loops of the samples annealed at 400℃ exhibited perpendicular anisotropy of large coercive force and high rectangle ratio, which decreased soft magnetic properties and resulted in a dramatic fall of GMI effect. The samples annealed at 540℃ showed excellent soft magnetic properties by nano-crystallization, and the transverse magneto-impedance effect was high to 102.7%.3. Complex permeability and equivalent circuits were used to demonstrate the magnetization processes, which were relevant to GMI effect. The applied DC field was to produce a damping in domain wall movements, which was responsible for the minus parallel RL arm in equivalent circuits. The relaxation frequency of the sample was about 12MHz, near which the maximum GMI effect happened.