Wangzhi Yuan

Giant magnetoimpedance effect in CuBe/NiFeB and CuBe/insulator/NiFeB electroless-deposited composite wires

The giant magnetoimpedance (GMI) effect of CuBe/NiFeB and CuBe/insulator/NiFeB composite wires prepared by electroless-deposition was investigated. The results showed that geometry dimension has a significant influence on the GMI effect of CuBe/NiFeB composite wire. As the NiFeB layer thickness approaches the skin depth of the NiFeB layer, maximum GMI will be expected; it reaches -23% at 1 MHz. After adding an insulator layer, the GMI ratios of CuBe/insulator/NiFeB composite wire were much higher than those of CuBe/NiFeB composite wire. The maximum GMI ratio of CuBe/insulator/NiFeB composite wire was 250% at 500 kHz-1 MHz. This result is related to current redistribution under the external magnetic field and the electromagnetic interaction between the conductive core and the ferromagnetic layer, and also is related to the skin effect and eddy current of the sample.

The GMI effect in nanocrystalline FeCuNbSiB multilayered films with a SiO2 outer layer

The giant magneto-impedance (GMI) effect in nanocrystalline FeCuNbSiB multilayered films was investigated. The multilayered films were deposited by magnetron sputter equipment with an additional SiO2 outer layer. The GMI ratio of multilayered films varied with the annealing temperature due to the changing orientation of the magnetic moments. The maximum GMI frequency of the nanocrystalline state was lower than that of the amorphous state, decreasing from 12.3 to 5.45 MHz. Ageing experiments were carried out for films with and without the insulator layer. It was seen that the GMI ratio of the multilayer film with a covered SiO2 layer was preserved well even after ageing.

Giant magneto-impedance and low-frequency magneto-resistance effect in NiFeB coated composite wires

Composite wires of 100 μ insulated CuBe wire plated with a layer of NiFeB were produced by electroless-deposition, and their magnetic properties were studied. The results showed that a good magneto-impedance (MI) effect can be obtained at relatively low frequency. The largest MI ratio (ΔZ/Z)max obtained is 250% at 500 kHz. Magneto-resistance effect was also observed at low frequency, with the (ΔR/R)max observed to be -8.5% at 540 Hz and 38.7% at 10 kHz. Results are discussed, and the equivalent resistance and inductance as the result of the NiFeB layer are taken into account.

Giant Magneto-Impedance Effect in Ni80Fe20 Composited Multilayers

The thickness effect on the magnetic properties and giant magneto-impedance (GMI) effect of the multilayer film are investigated. The proportion of the perpendicular magnetization component in ferromagnetic layers and the interfacial effect in multilayers are the reasons of the phenomenon.

Magneto-impedance effect in NiFeP/CuBe electrodeless-deposited wires by dc Joule annealing

In this present work, NiFeP/CuBe composite wires were produced by electrodeless-depositing a layer of 1.5 /spl mu/m NiFeP on CuBe wires of 100 /spl mu/m in diameter and 5 cm in length. The composition of NiFeP layers was Ni/sub 76/Fe/sub 18/P/sub 6/, determined by ICP spectrometry system. The composite wire samples were annealed in a furnace or using a dc Joule annealing technique, in which under the protection in the environment of argon gas, the composite wire has a DC current passing through it for certain time. The crystallization process of the wires was studied by X-ray diffraction. MI measurements on the composite wires were carried out using a precision impedance analyzer.