Analysis of asymmetric giant magnetoimpedance in field-annealed Co-based amorphous ribbon

Abstract

The asymmetric giant magnetoimpedance (GMI) profile has been realized in weak-field-annealed Co-based amorphous ribbon at the annealing temperature of 380 °C in open air. Asymmetric GMI profiles with respect to applied field become profound as the annealing field increases over 500 mOe. The asymmetric GMI profile at the frequencies of ac current over 0.5 MHz is well ascribed for by the rotational transverse magnetization of single domain under a uniaxial anisotropy in amorphous core and a unidirectional anisotropy due to the exchange coupling with the bias field in the crystalline layer, underlying surface oxidation layer developed during the annealing in open air.

Air-oxidation of a Co-based amorphous ribbon at 400–600°C

“…A typical result shown in the literature is to have an ultra-high fracture strength of 5185 MPa for a Co 43 Fe 20 Ta 5.5 B 31.5 amorphous alloy [4]. Furthermore, particular examples of interest are to use them for the soft magnet-tube and micro-electronic core applications [5,6]. Besides, it may be also important to understand their thermal-activated degradation in oxidizing atmospheres when using those alloys at elevated temperatures in ambient environments.…”

The diagnosis of thermal aged inconel 600 using giant magnetoimpedance (GMI) sensor

“…I600 alloy is normally nonmagnetic, but it has little magnetic response under the operating condition of steam generator [2]. Recently developed Co-based amorphous giant magnetoimpedance (GMI) sensor shows the high field sensitivity over 1000%/Oe [3]. In this study, the change of GMI signals were measured in the thermal aged I600 alloy as a function of ageing time at various temperatures.…”

Prototype Milli Gauss Meter Using Giant Magnetoimpedance Effect in Self Biased Amorphous Ribbon

“…We reported that the asymmetric GMI effect in the field-annealed ribbon due to the bias field produced by hard magnetic layer formed near the surface during annealing [5,12].…”