Magneto-impedance of glass-coated Fe–Ni–Cu microwires

Abstract

The magneto-impedance (MI) of glass-coated Fe-Ni-Cu microwires was investigated for longitudinal radio-frequency (RF) currents up to a frequency of 200 MHz using an RF lock-in amplifier method. The MI, defined as ∆Z/Z = [Z(H)-Z(H=0.3T)]/Z(H=0.3T), displays a peak structure (negative MI) at zero field for RF currents with frequencies less than 20MHz and this crosses over to a sharp dip (positive MI) at higher frequencies. This crossover behavior is ascribed to the skin-depth-limited response primarily governed by the field-dependence of the permeability. Large saturation fields (300 to 600 Oe) and other anomalies indicate the possible influence of giant magneto-resistance (GMR) on the MI. a) Corresponding

Density and Surface Tension of Liquid Ternary Ni–Cu–Fe Alloys

“…In recent years, the Ni-Cu-Fe ternary system received some attention for its electrical and magnetic properties [1,2]. The combination of its low thermal expansion and its relatively high electrical and thermal conductivity makes Ni-Cu-Fe also an interesting candidate for the development of new data storage facilities [3].…”

A Position Sensor Based on Magneto-Impedance Effect

“…The high-frequency ac current has the magnitude I high ¼ 20 mA at frequency f high ¼ 1 MHz; the low-frequency ac current has the magnitude I low ¼ 5 mA at frequency f low ¼ 400 Hz. It can be seen that the PW behaves in a very similar way to the impedance of the wire Z as a function of external dc magnetic field H ex [4,5]. At these measurement conditions, a large sensitivity in GMI was obtained.…”

“…The GMI effect can be defined as the change of impedance of a soft magnetic element carrying a high frequency current with external dc magnetic field. The origin of GMI is electromagnetic dynamics accompanied with skin effect and it is related to changes in the dynamic magnetization processes that effect the magnetic transverse permeability and therefore the flux penetration depth due to ac current through the sample with high frequencies.In the application of the GMI effect, commonly an ac current is applied to an amorphous alloy [4,5], the amplitude of the induced voltage e L between the ends of the wire is measured as a function of an external static applied magnetic field H ex parallel to the wire axis. In this paper, an alternated measurement method for GMI effect is presented and the development of such a method as a position sensor is also discussed.…”

“…In the application of the GMI effect, commonly an ac current is applied to an amorphous alloy [4,5], the amplitude of the induced voltage e L between the ends of the wire is measured as a function of an external static applied magnetic field H ex parallel to the wire axis. In this paper, an alternated measurement method for GMI effect is presented and the development of such a method as a position sensor is also discussed.…”

“…Recently, Valenzuela et al [3] have presented position sensor based on magneto-impedance effect. This effect has received considerable attention because of its applications as magnetic sensors in many applications [4,5]. The GMI effect can be defined as the change of impedance of a soft magnetic element carrying a high frequency current with external dc magnetic field.…”