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

Shengdi Sun,Bo Zhang,Wenjie Ding,Shuling Zhang

doi:10.1155/2016/6465235

Abstract

Co68.25Fe4.5Si12.25B15amorphous microwires with a diameter of 34 μm were prepared via the melt extraction method. The dependency of AC driving currentIacand 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 whenIacchanged 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 inIacunder direct magnetic field when the frequency was below megahertz. However, MTKI values were similar with the increase ofIacwhen it was over 2 MHz. Meanwhile, the GMI effect was optimized by selecting an adequate value of AC driving currentIp, at which the circular permeability was higher when the frequency was not over 2 MHz. Results showed that the influence ofIacon magnetoimpedance became weak with strong skin effect and slightly stronger GMI effect driven by a higherIacwhen 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.

Highlights

Giant magnetoimpedance (GMI) effect refers to the strong and sensitive change of impedance of a magnetic conductor with a small variation in DC magnetic field [1, 2]
The origin of GMI effect in microwires has been interpreted in terms of skin effect and variation in circumferential permeability caused by axially applied DC magnetic field
RDC J0 2J1 where RDC is the direct resistance of microwire and J0 and J1 are the Bessel functions. k is defined as k = (1 + j)/δ, j is the imaginary unit, and δ is the penetration depth which is given by the following function: δ= 1, √πσμΦf where σ is the electrical conductivity and μB is the circular permeability

Summary

Introduction

Giant magnetoimpedance (GMI) effect refers to the strong and sensitive change of impedance of a magnetic conductor with a small variation in DC magnetic field [1, 2]. The excellent soft magnetic property and uniform diameter are the advantages of melt-extracted wires, making them more suitable for sensor applications without glass cover. Their GMI effect is excellent [11]. The dependency of AC driving current on magnetization and GMI effect is investigated in a frequency range of 0.1 MHz to 15 MHz. A rich variety of multipeak features in GMI response depended on the driving current within a small DC magnetic field range, which have been observed and discussed

Experimental Details

Results and Discussion

10 MHz 15 MHz

Conclusions