Zirong Wu

Resonance Enhancement of the Giant Magnetoimpedance Effect in Glass-Coated Microwires With Outer Conductive Layer

We investigated resonance enhancement of the giant magnetoimpedance effect in Fe-based glass-coated microwires with an outer copper layer. We found that a capacitance forms between the ferromagnetic core and the outer conductive layer, where the glass insulator works as a dielectric layer. The composite wire formed an LC resonance circuit by itself, resulting in an increase of magnetoimpedance ratio from 250% to 330%. Here, we explain the results in terms of the LC resonance enhancement principle.

High temperature magnetic studies of nanocrystalline Fe69.5(CuCrV)9.5Si13B8

Abstract Nanocrystalline Fe 69.5 (CuCrV) 9.5 Si 13 B 8 were prepared by annealing amorphous Fe 69.5 (CuCrV) 9.5 Si 13 B 8 ribbons at a series of temperatures. Hysteresis loops of the selected samples were measured as a function of the temperature. A distinct point of inflection is found in the temperature dependence of the reduced magnetization. The 540°C annealed sample has the lowest coercivity at room temperature; With increasing temperature, the coercivity values of the annealed samples rise drastically. This is associated with the magnetic coupling between the grains through the amorphous boundary.

Enhancement of giant magento-impedance effect using LC resonance

In this study, resonance enhancement of giant magneto-impedance (GMI) effect in Fe-based Fe73.5Cu1Nb3Si13.5B9 glass-coated microwires was investigated. A new method was adopted by sputtering a copper layer in the outside of the Fe-based glass-coated wire. A capacitance forms between the ferromagnetic core and outer copper layer, where the glass insulator works as a dielectric layer. Therefore, the composite wire forms an LC resonance circuit (which consists of an inductor, represented by the letter L, and a capacitor, presented by the letter C) itself, resulting in an increase of GMI ratio from 250% to 330%. Meanwhile, the influence of resonance frequency on the GMI effect was discussed.

Influence of dc Joule Annealing on Magnetoimpedance of CuBe/CoNiP Composite Wires

In this paper, the influence of dc Joule annealing on giant magnetoimpedance (GMI) effect for composite wires by electroless depositing 12 mum thickness CoNiP layer on CuBe wires with 150 mum in diameter is presented. Successive thermal treatments by dc Joule annealing with current density ranging from 1.13 to 2.83 x 108 A/m2 are applied to the composite wires with 5 cm in length for a constant annealing time of 10 min. MI measurements are carried out using an impedance analyzer (HP4294A), the rms value of the ac driving current was kept constant at 5 mA.