Improvement of giant magneto impedance of Co-rich melt extraction wires by stress-current annealing

Abstract

In order to improve the giant magneto impedance (GMI) of Co-rich wires for high sensitive sensor applications, Co 68 Fe 4.5 Si 15 B 12.5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile stresses applied. And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz. It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments, because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy, which improved the circular permeability and GMI effect. Their impedance ratio ΔZ/Z increased from 244% to 480.9% at 7 MHz and the field sensitivity increased to 0.83%/(A/m) at 5 MHz, when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min. It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.

Investigation the Effect of Sample Length in Different Currents and Frequencies of Measurement on the Magneto Impedance, Sensitivity and Extinction Field of Amorphous Cobalt Based Ribbons

“…Where S is the sensitivity, dMI, the change in magnetic impedance, and dH, is the change in the external field of action applied to the sample. Another important parameter is the extinction field, and this field is field in which the magnetic impedance reaches 1/e [6]. The extinction field for both samples was obtained using origin software.…”

“…Magnetic impedance has usage in sensors, and sensors based on magnetic impedance [7], [8]. are highly sensitive [1], [2], [6]. Annealing, polishing, coating, and stressing methods are used on the sample to increase magnetic impedance changes and thus increase the sensitivity of the sensors [3].…”

Large negative tension-impedance effect in a soft ferromagnetic microwire

“…Consequently, the crosssectional area of the conductor may show a slight influence on the impedance, while the circumferential permeability variation caused by the internal tensile stress is probably the main contribution to the impedance reduction at high frequency. It is generally believed that the internal stresses in soft magnetic materials have an important influence on effective permeability [18][19][20][21][22][23]. The stronger the internal tensile stress, the greater the reduction of the circumferential permeability, and the larger the reduction of the impedance.…”

Influence of Laser-Induced Surface Morphology on the Magnetic Domains of CoFeSiB Amorphous Ribbons

“…They are known as soft magnetic materials with high magnetic permeability. However, to become appropriate candidates for magneto-impedance (MI) and magneto-elastic sensors, further improvement of their magnetic properties by specific annealing methods is desirable [4][5][6][7][8][9][10]. The application of these materials requires a detailed knowledge of the crystallization and kinetic behaviour [11].…”