MI-Sensor Element Features and Estimation of Penetration Depth and Magnetic Permeability by Magnetoresistance and Magnetoreactance of CoFeSiB Amorphous Wires

The magnetoimpedance (MI) of amorphous soft magnetic Co68.15Fe4.35Si12.5B15 wires produced by the in-rotating water quenching technique was systematically studied. The behavior of the MI-element designed for magnetic sensors was examined in an external longitudinal dc magnetic field in the low-frequency range (f <= 1 MHz) and at the beginning of the intermediate-frequency range (2 MHz <= f <= 5 MHz). A critical frequency of about 5-7 kHz was observed with an initial increase in the MI effect. A maximum MI ratio of 334% was recorded at 0.95 MHz in a magnetically saturated MI element. The intermediate-frequency range is explored using the magnetoresistive (MR) and magnetoreactive (MX) components of MI Z. The MI anisotropy field profile occurs in the MHz operating frequency range with values increasing up to 25 A/m, exhibiting frequency dependence. The magnetic penetration depth was calculated using experimental magnetoresistance data, and the values obtained were about 3-4 mu m for 5 MHz, showing a saturation trend. The magnetic permeability is analyzed in the framework of the electromagnetic classical high limit model of a cylinder, which includes penetration depth and magnetoreactance. In our experiments and calculations, the classical high limit is satisfied in the operating frequency range of a few MHz. The magnetic permeability peak value is about 35% lower than the comparable data of amorphous CoFeNiMoSiB glass-coated microwires.

Automated summary

The magnetoimpedance (MI) of amorphous soft magnetic Co68.15Fe4.35Si12.5B15 wires produced by the in-rotating water quenching technique was systematically studied. The behavior of the MI-element designed for magnetic sensors was examined in an external longitudinal dc magnetic field in the low-frequency range (f <= 1 MHz) and at the beginning of the intermediate-frequency range (2 MHz <= f <= 5 MHz). A maximum MI ratio of 334% was recorded at 0.95 MHz in a magnetically saturated MI element.