Study of Stress Annealing on Giant Magneto-Impedance in Glass-Covered Co-Based Amorphous Microwires

The glass-covered Co-rich amorphous wires was annealed by an applied stress during the current annealing process. The influence of stress and dc current annealing on the giant magneto-impedance (GMI) effect were investigated by the magneto-impedance. Our experiments showed that the magentic anisotropy is reduced by the annealing treatments, furthermore, the maximum GMI value is increased to 105 %.The GMI value is enhanced by increasing the outer domain volume and inducing a transverse anisotropy due to the changing of inner stress.

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Influence of Pulsed Current Annealing on Giant Magneto-Impedance Effects of Co Based Amorphous Ribbon

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.311-313.2035 ◽

2011 ◽

Vol 311-313 ◽

pp. 2035-2039

Author(s):

Feng Jiang ◽

Bing Hao Bao

Keyword(s):

Current Density ◽

Amorphous Ribbon ◽

Anisotropy Field ◽

Critical Value ◽

Pulsed Current ◽

Transverse Anisotropy ◽

Gmi Effect ◽

Driving Current ◽

Giant Magneto Impedance ◽

Current Annealing

In this paper, the influence of pulsed current annealing on giant magneto-impedance (GMI) effect of Co66.3Fe3.7Si12B18 amorphous ribbon under different driving current is studied. The experiment results show that the GMI effect is closely related to the annealing current density. With the increase of annealing current density, the GMI ratio ΔZ/Z rises firstly and the maximal GMI ratio of 53.8% is obtained for the sample annealed at 104A/mm2. When annealing current density increases further, the GMI ratio begins to decrease. The mechanism of the pulsed current annealing affecting the GMI effect is explained qualitatively. This paper also discusses the influence of transverse anisotropy field HK induced by annealing on GMI effect. Proper transverse anisotropy field benefits the enhancement of the maximal GMI ratio, however, the GMI ratio will begin to fall as soon as exceeding the critical value.

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Comparison between ac and dc current annealing in CoFeSiB glass-covered amorphous microwires

Journal of Physics D Applied Physics ◽

10.1088/0022-3727/40/10/031 ◽

2007 ◽

Vol 40 (10) ◽

pp. 3233-3238 ◽

Cited By ~ 14

Author(s):

K D Sossmeier ◽

F Bohn ◽

H Chiriac ◽

M Carara

Keyword(s):

Current Annealing ◽

Amorphous Microwires ◽

Dc Current

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Влияние токового отжига на температурные зависимости магнитоимпеданса в аморфных микропроводах

Журнал технической физики ◽

10.21883/jtf.2019.07.47798.411-18 ◽

2019 ◽

Vol 89 (7) ◽

pp. 1050

Author(s):

А. Джумъазода ◽

Л.В. Панина ◽

М.Г. Неъматов ◽

Н.А. Юданов ◽

Ф.С. Табаров ◽

...

Keyword(s):

Magnetic Field ◽

High Performance ◽

Thermal Stabilization ◽

Central Peak ◽

Magnetic Sensors ◽

Intermediate Temperature Range ◽

Amorphous Wires ◽

Amorphous Microwires ◽

Dc Current ◽

External Stimuli

Miniaturization of material’s size is the key feature in many technological applications, in particular, in sensor systems. To achieve this goal, Taylor-Ulitovski technique was employed to produce microwires with very small (from 0.2 up to 100 µm) diameters. Ferromagnetic amorphous microwires exhibit giant magnetoimpedance effect (GMI) which is useful to develop high performance magnetic sensors. Since the discovery of GMI, a considerable amount of interest was devoted to enhancing sensitivity with respect to various external stimuli (magnetic field, stress, temperature). On the other hand, GMI sensing elements should have high environment stability. In the present work, a comprehensive study of the temperature effects on the magnetoimpedance behavior in amorphous microwires is conducted. The wires under investigations of the composition Co60.51Fe3.99Cr12.13B13.53Si9.84 have a relatively high Curie temperature (>300 ℃) but may demonstrate considerable temperature dependence in the intermediate temperature range (<100 ℃) of dc and ac magnetic properties. We showed that the as-casted wires exhibited a notable change in magnetic anisotropy, from circumferential to an axial anisotropy, owing to the internal stress relaxation. This is accompanied by huge variation in the magnetoimpedance behavior: the impedance vs magnetic- field plots change shape: from two symmetrical peaks to a single central peak. Current annealing (dc current of 25 mA magnitude for 60 min) was proposed to achieve a thermal stabilization of the magnetization processes and magnetoimpedance in glass-coated amorphous wires.

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