Magnetization and Giant Magnetoimpedance Effect of Co-Rich Microwires under Different Driven Currents

Co68.25Fe4.5Si12.25B15 amorphous microwires with a diameter of 34 mu m were prepared via the melt extraction method. The dependency of AC driving current I-ac and frequency on giant magnetoimpedance (GMI) effect and magnetization were investigated using a 4294A impedance analyzer and the transverse Kerr effect. The GMI effect was analyzed when I-ac changed from 6 mA to 20 mA at a frequency ranging from 0.1 MHz to 15 MHz. The influence of AC current dependent on the frequency is correlated with the magnetization mechanism. The maximum transverse Kerr intensity (MTKI) decreased with the increase in I-ac under direct magnetic field when the frequency was below megahertz. However, MTKI values were similar with the increase of I-ac when it was over 2 MHz. Meanwhile, the GMI effect was optimized by selecting an adequate value of AC driving current I-ac at which the circular permeability was higher when the frequency was not over 2 MHz. Results showed that the influence of I-ac on magnetoimpedance became weak with strong skin effect and slightly stronger GMI effect driven by a higher I-ac when the frequency was between 2 MHz and 15 MHz. The skin effect turned out to be the key factor to the GMI effect; thus, there were no obvious differences in magnetization and GMI effect with AC driving current changing when the frequency was as high as 15 MHz.