Metal-to-glass ratio and the Magneto-Impedance of glass-covered CoFeBSi microwires at high frequencies

TL;DR

This study investigates how the metal-to-glass ratio influences the high-frequency Magneto-Impedance of glass-covered CoFeBSi microwires, revealing peak MI behavior at specific frequencies and ratios, and providing a thermodynamic interpretation.

Contribution

It introduces a detailed analysis of the effect of metal-to-wire diameter ratio on high-frequency MI in glass-covered microwires, supported by a thermodynamic model.

Findings

Maximum MI occurs at specific frequencies for different diameter ratios.

The MI exhibits twin-peak, anhysteretic behavior as a function of magnetic field.

The thermodynamic model clarifies the influence of the diameter ratio on MI and anisotropy.

Abstract

High frequency [1-500 MHz] measurements of the Magneto-Impedance (MI) of glass-covered Co$_{69.4}$Fe$_{3.7}$B$_{15.9}$Si$_{11}$ microwires are carried out with various metal-to-wire diameter ratios. A twin-peak, anhysteretic behaviour is observed as a function of magnetic field. A maximum in $\Delta Z/Z$ appears at different values of the frequency $f$, 125, 140 and 85 MHz with the corresponding diameter ratio $p$ = 0.80, 0.55 and 0.32. We describe the measurement technique and interpret our results with a thermodynamic model that leads to a clearer view of the effects of $p$ on the maximum value of MI and the anisotropy field.