J. Z. Ruan

East China Normal University, Shanghai, Shanghai Shi, China

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Publications (9)13.49 Total impact

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    ABSTRACT: In this paper, a new method for fabricating Ni80Fe20/Cu composite wires is presented. A series of samples were prepared by alternating the rotating direction of the Cu wire during RF magnetron sputtering. In order to keep the overall coating thickness of all the samples constant, the alternating intervals and rotating period of each sample during sputtering were varied. As the rotating period increased, the samples showed different magneto-impedance profiles. Experimental results indicated that there was a critical thickness for single sputtered layer which the MI ratio was significantly enhanced at a relatively low driven current frequency. Qualitative discussion on these phenomena was explained in terms of exchange interaction and electromagnetic interactions.
    Surface Review and Letters 01/2011; 18(06):223-227. · 0.28 Impact Factor
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    ABSTRACT: In this work, magnetron sputtering in the form of continuous deposition or intermittent deposition modes was used to obtain NiFe/Cu composite wires. Based on the results, intermittent deposition mode led to the formation of an interface between deposited layers. A better crystallite and a little grain growth were found for the intermittently deposited wire. Good soft magnetic properties and large giant magneto-impedance (GMI) effect were exhibited by both composite wires. The GMI profile for the intermittently deposited composite wire was characterized by two peaks, which could be attributed to the difference in the magnetic properties of the inner and the outer magnetic layers. Annealing was introduced to the intermittently deposited wire so that the inherent stresses were partially relaxed. As a result, its GMI effect was enhanced and the magnetic properties of the two magnetic layers became similar. Hysteresis loops of the composite wires displayed different magnetic behaviors and hence further affirmed the GMI results.
    Physica B Condensed Matter 01/2008; 403:3054-3058. · 1.28 Impact Factor
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    ABSTRACT: In this work, Ni80Fe20/Cu composite wires of length 50 mm, consisting a Cu core of diameter 100 μm, coated with a layer of Ni80Fe20, were produced by RF magnetron sputtering. To obtain a uniform coating, the wires were spun during sputtering by a homemade system. The results showed that the spinning speed might affect the maximum MI ratio and the magnetic properties. The MI ratio of the sputtered wires increases with the wire spinning speed in the magnetron sputtering. The film thickness had a significant effect on the magnitude and the optimum frequency of the giant magneto-impedance effect. The maximum MI ratio can reach about 247.4% for the specimen with a Ni80Fe20 coating thickness of 2.81 μm at 400 kHz. This large MI effect, obtained at such low frequency range, was correlated with the electromagnetic interaction between the inner core and the magnetic coating.
    Surface Review and Letters 01/2008; 15(06):753-756. · 0.28 Impact Factor
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    ABSTRACT: CuBe/NiFeB and CuBe/Insulator/NiFeB composite wires have been prepared by electroless-deposition. The giant magnetoimpedance (GMI) effect for NiFeB layer with thickness of 3μm on CuBe core with diameter of 100μm has been studied. After adding an insulator layer, the maximal GMI ratio of CuBe/Insulator/NiFeB composite wire is much higher than that of CuBe/NiFeB composite wire, and can reach to about 250% at the frequency range of 500kHz–1MHz. The results are explained in terms of difference of magnetic structure and different frequency dependence of resistance and reactance of the two kinds of composite wires.
    Journal of Magnetism and Magnetic Materials 01/2007; 308(2):269-272. · 1.83 Impact Factor
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    ABSTRACT: The giant magneto-impedance and skin effect in electroless deposited CuBe/CoNiP composite wires with different diameter of CuBe core are presented, and involves a theoretical approach of the current density distributions in layers. Results show that the strong eddy current in the magnetic CoNiP coating will be induced due to the electromagnetic interactions with the CuBe core. It makes the skin effect strong in the magnetic coating even at very low frequency, and at this, large MI changes can also be observed.
    Journal of Magnetism and Magnetic Materials 01/2006; 305(1):212-215. · 1.83 Impact Factor
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    ABSTRACT: 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.
    Journal of Physics D Applied Physics 04/2005; 38(9):1351. · 2.53 Impact Factor
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    ABSTRACT: The investigation of the nanocrystallization and magnetic properties of FeCuNbSiB films by X-ray diffraction (XRD) and Mössbauer spectrum is presented in this paper. The XRD results showed that the films begin to crystallize at 400°C. The nanocrystalline volume fraction of the samples and the orientation of the magnetic moments could be obtained by the Mössbauer spectrum. From as-deposited state to the sample annealed at 570°C, the magnetic moments of the films were orientated from the initial direction parallel to the film plane to the direction perpendicular to it, and later back. Eventually, moments orientations of the film samples were random. The magnetic studies also revealed the moments orientations during the heat treatment. The giant magneto-impedance (GMI) ratio of sandwiched films varies with changing orientation of magnetic moments. When the orientation of moments was perpendicular to the film plane, the GMI ratio decreased dramatically.
    Journal of Magnetism and Magnetic Materials 01/2004; 279(2):429-434. · 1.83 Impact Factor
  • Source
    Z J Zhao, Y Z Fang, J Z Ruan, X L Yang
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    ABSTRACT: Resonance frequency f r of a LC circuit composed of a capacitor and a small solenoid, which contains Fe-based nanocrystalline powder cores, was measured. The properties of resonance frequency f r shift dependence on external magnetic field, H ex ; have been investigated. The results showed that f r evidently increases with H ex and exhibits good linearity and sensitivity in the low field range. The large frequency shift is another form of giant magneto-impedance effect. The method can be used for measuring magnetic field or for improving the sensitivities of magnetic sensors. r 2003 Elsevier B.V. All rights reserved.
    Journal of Magnetism and Magnetic Materials 01/2004; 278:82-86. · 1.83 Impact Factor
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    ABSTRACT: The giant magneto-impedance (GMI) effect for Fe73.5Cu1Nb3Si13.5B9 nanocrystalline ribbons is investigated in the temperature range between room temperature and 873 K. The thermal dependence of GMI effect reveals the enhancement of Curie temperature of the amorphous matrix, reflecting the exchange coupling between the α-FeSi grains as well as the compositional changes of the amorphous matrix itself. However, the dipolar interaction between grains is suggested to be responsible for the non-zero GMI effect after the magnetic phase transition of the amorphous matrix.
    Journal of Magnetism and Magnetic Materials 01/2002; · 1.83 Impact Factor