Study On The Giant Magneto-impedance Effect In Ni₈₀Fe₂₀ Composite Multilayers

Due to the extensive application perspective of the giant magneto-impedance (GMI) effect devices and the importance of the composite multilayers in the GMI effect, we have designed and deposited the multilayers samples depending on the material characteristic of Ni₈₀Fe₂₀. The geometrical structures of them are as follows:(Ni₈₀Fe₂₀/SiO₂)_n/Cu/(SiO₂/Ni₈₀Fe₂₀)nand (Ni₈₀Fe₂₀/Cu)_n /SiO)₂/Cu/ SiO₂ /(Cu/ Ni₈₀Fe₂₀)nBy the X-ray diffraction spectrums and the hysteresis loops, we studied the change of the samples' crystallization structure, magnetism characteristic and GMI effect, which were induced by the geometrical structure. The main results are explained further.1. In the samples of the (Ni₈₀Fe₂₀/SiO₂)n/Cu/(SiO₂/Ni₈₀Fe₂₀)n composite multilayers, when the structure of (SiO₂/NiFe)_n (n>1) was used, the perpendicular component of the magnetization diminished with decreasing thickness of the Ni₈₀Fe₂₀ monolayer. And as a result, the GMI effect of the samples enhanced with increasing number of layers n of bilayers SiC>2/NiFe. At n=3, the maximum LMI ratio is 10.81%, while the maximum TMI ratios is 17.08%. And when n increases to 4 and 5, the interfacial effect turned to be dominant, and the MI ratios decrease slightly compared with the ratios at n=3.2. When the Cu layers were used as separate layers in the samples with the structures of (Ni₈₀Fe₂₀/Cu)_n/SiO₂/Cu/SiO₂/(Cu/Ni₈₀Fe₂₀)_n, the perpendicular component of the magnetization diminished with decreasing thickness of the Ni₈₀Fe₂₀ monolayer, and the GMI effect of the samples obviously enhanced. Because the crystal structure of Cu is familiar with the Ni₈₀Fe₂₀, the MI ratios didn't appear to decrease compared with the ratios at n=3, when n increases to 4 and 5.