Giant Magnetoimpedance of Glass-Covered Amorphous Microwires of Co-Mn-Si-B and Co-Si-B

TL;DR

This paper investigates the magnetic hysteresis and giant magnetoimpedance (GMI) effects in glass-covered amorphous Co-Si-B and Co-Mn-Si-B microwires, revealing how magnetostriction influences their magnetic behavior and impedance response across frequencies.

Contribution

It provides a comparative analysis of GMI and hysteresis in wires with different magnetostriction, highlighting the effects of magnetostriction sign on magnetic and impedance properties.

Findings

Positive MS wires show rectangular hysteresis loops.

Impedance peaks at zero field for positive and zero MS wires.

Negative MS wires exhibit impedance maxima at finite fields with small currents.

Abstract

A study of magnetic hysteresis and Giant magnetoimpedance (GMI) in amorphous glass covered Co-Si-B and Co-Mn-Si-B wires is presented. The wires, about 10 microns in diameter, were obtained by glass-coated melt spinning technique. Samples with positive magnetostriction (MS) have a rectangular bistable hysteresis loop. A smooth hysteresis loop is observed for wires with nearly zero MS. When MS is negative, almost no hysteresis is observed. The GMI was measured in the frequency range between 20 Hz and 30 MHz. The shapes of the impedance versus field curves are qualitatively similar to each other for both positive and zero MS samples. Impedance is maximum at zero field, and decreases sharply in the range 10-20 Oe. For the negative MS wires, when the driving current is small, the impedance is maximum at a finite external field. The position of the maximum approaches zero with increasing current. The contributions of the moment rotation and domain wall motion in the three cases are discussed.