直流偏置电流对钴基非晶带环形磁芯巨磁阻抗效应的影响

将近零磁致伸缩系数的Co66.3Fe3.7Si12B18非晶薄带卷成环形后,在200Gs横磁场作用下,用密度为25A/mm2的脉冲电流退火30s,在穿过环形薄带圆心的直流电流产生的圆周磁场作用下的巨磁阻抗效应.激励电流频率f＞100kHz时,阻抗随圆周磁场的变化呈现对称双峰曲线;最大阻抗变化率（GMI）max随频率的升高而增大,当频率f=2MHz,幅值Ip=10mA时,（GMI）max=57%.直流偏置电流改变了非晶带横向磁导率,造成阻抗变化的不对称.偏置电流较小时,阻抗变化曲线的一边峰值得到加强,另一边峰值减弱;偏置电流较大时,两峰值都被削弱.阻抗变化的不对称性与激励电流的频率和直流偏置电流大小有紧密联系.

Effect of DC Bias-Current on Giant Magneto-Impedance of Co-Based Amorphous Ribbon Toroidal Core

The giant magneto-impedance effect has been measured in near-zero magnetostriction Co_(66.3)Fe_(3.7)Si_(12)B_(18) amorphous ribbon toroidal core annealed with 25A/mm~2 pulse current density under a transverse magnetic field of 200Gs for 30 seconds.The circular magnetic field was supplied by DC current through the center and parallel to the axes of the toroidal core.GMI ratio profile shows symmetric two peaks for f>100kHz at zero DC bias current.The maximum GMI ratio increases continuously with frequency of AC driving current up to 57% at 2MHz with amplitude of 10mA.Asymmetric GMI profile appeared with the transverse permeability changed by the magnetic field induced by the DC bias current.One peak enhanced and the another diminished in low DC bias current and two peaks both diminished in strong value.Asymmetric GMI ratio profile dependence on frequency and DC bias current is analyzed.