张怀武
磁电信息材料与器件、磁性纳米材料芯片和微磁LTCC集成器件方向
个性化签名
- 姓名:张怀武
- 目前身份:
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学术头衔:
博士生导师, 国家杰出青年科学基金获得者
- 职称:-
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学科领域:
微电子学
- 研究兴趣:磁电信息材料与器件、磁性纳米材料芯片和微磁LTCC集成器件方向
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379
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成果数
7
【期刊论文】Electric and Magnetic Properties of a New Ferrite-Ceramic Composite Material
张怀武, ZHANG Huai-Wu, SHI Yu, ZHONG Zhi-Yong
CHIN. PEYS. LETT. Vol. 19, No.2 (2002) 269,-0001,():
-1年11月30日
We hane investigated a new ferrite-ceramc composite material with inductive and capacitive properties fahcicated by a solid-state reaction method. We analyse the effects of the composite mechamism and microstrocture on the magnetic and electric properties. The resuits show that the new materials can be used not only as in ductor materials. but also as capacitor materials in the wide frequency range of 1kHz-1.8GHz. The real part of permeability of the composite material is between 10 and 5.6, the imagimary part of permeability is between 1.2 amd 0.5, and the dielectric constan isabout ten times larger than that of ordinary ferricte materials. It is suggested that the new composite materials will be widely used in anti-electromagnetic interference fields and radio frequency communication fields.
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【期刊论文】An improved microchip thin lm transformer formed by vacuum evaporation and sputtering
张怀武, H.W. Zhang*, Y.L. Liu, Z.Y. Zhong
Vacuum 62(2001)1-6,-0001,():
-1年11月30日
A microchip thin film transformer which is composed of an I-shaped [CoZrNb/SiOχ]m magnetic layer and wound with Cu thin film coils fabricated by using a mask vacuum evaporation and sputtering composited process has been investigated. Comparing the CoZrNb core with [CoZrNb/SiOχ]m core of thin lm transformer, it is shown that the multilayer thin films have more advantages than a single magnetic layer in their of soft magnetic properties, especially the permeability (μ) and coercivity (He). The microchip transformer has a relatively high inductance of 0.4-1.0μH for a ratio of primary turns to secondary coil turns of 3:1 and 3:2, and has a high Q value of 4-12. The thin film transformer can be operated in an integrated micro-switching converter at a frequency between 1kHzand 10MHz.
Microchip device, Thin film transformer, Multilayer, Soft magnetic films
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【期刊论文】Improvement of thin "lm transformer characteristics by use of a new fabrication process
张怀武, H.W. Zhang*, Z.Y. Zhong, Y.L. Liu, H.C. Wang
Vacuum 55(1999)197-200,-0001,():
-1年11月30日
A new thin "lm transformer which is composed of an E-shaped CoZrRe magnetic layer and wound with Cu thin" lm coils fabricated by using a mask vacuum evaporation process has been investigated. The ratio of primary coil turns to secondary coil turns is 3:1 and 3:2. The transformer has a relatively high inductance of 0.4-0.8μH, and can be operated in an integrated micro-switching converter at frequencies between 100KHz and 10MHz.
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张怀武, Huai Wu Zhang, Y L Liu and H C Wang
Vacuum/volume 48/number IO/pages 857 to 860/1997,-0001,():
-1年11月30日
The nitrogen ions were implanted in 17pm thick soft magnetic ribbon at a dose range between 1019 and 1021 ions per square metre. The implanted samples were annealed at about 655K for 1h in a vacuum (0.1Pa). The result showed that the effective permeability increased and the coercivity decreased with implanted dose increasing in the frequency range of about 50KHz to 8MHz, whereas the soft magnetic properties deteriorated when the implanted dose was low-1018 ions per square metre, which may be related to finely dispersed metal-N precipitates, the metal-N phase could act as nucleation or pinning sites, suppressing the growth of a-Fe grains and increasing the nucleus formation.
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【期刊论文】Micromagnetics and Signal Analysis of Shielded Spin-Valve Multilayer
张怀武, ZHANG Huai-wu, YANG Shi-oing, LIU Ying-li, WANG Hao-cai, H.J. Kim
CHIN. PHYS. LETT. Vo1. 13, No.6 (1996) 469,-0001,():
-1年11月30日
In order to linearize a spin-valve giant magnetoreslstance head, the exchanges layer sputtered at fringe area or a permanent magnet layer longitudinal biasing for domain stabilization based on a physical calcalated mode/may be considered. The corre/ations between the head performance characteristic and head geometric parameters have been simulated by putting the head on a suitable front-end electric circuit. The simulative results show that the optimal sensing current is from 10 to 40mA and the near geometric parameteres for gap width are at the range of G1+G2<0.5μn.
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张怀武, Huai-Wu Zhang and S Q Yang.
Vacuum/volume 46/number 7/pages 661 to 66611995,-0001,():
-1年11月30日
The manner in which the coercivity, permeability and resistivity of films of Fe-M-X (Tvl : Ta, Hf, Zr, Nb; X: N, C, Ar;) and Permalloy varied because of particular conditions during DC magnetron sputter deposition has been determined. The effects of reactive gases and substrate bias during the sputtering process were studied and the measured values for H, p and p were compared with the results from formulae derived from gas impurity pinning and scattering theory. For Fe-M-X films, the coercivity could be modified from 1.2 Oe to 0.4 Oe and the permeability from 3
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张怀武, Huai-Wu Zhanga, H. J. Kim b, S.Q. Yanga
Materials Science and Engineering B34(1995)53-57,-0001,():
-1年11月30日
The rapid thermal annealing method is used to crystallize a glass/A1/BiGaDylG double-layer film (where BiGaDylG denotes dysprosium iron garnet films doped with Bi and Ga); the effective Faraday angle of the double-layer film is about 0.25° greater than that for glass/BiGaDyIG film and about 0.15° greater than that for common glass/BiGaDyIG/A1 double films in a wide thickness range; meanwhile the Curie point is decreased because of the aluminium atoms diffusing into the garnet film and substituting at octahedral and tetrahedral Fe3+ sites. The Curie temperature can be adjusted between 161 and 140℃ by means of delay annealing duration. The grain diameter and Faraday angle as functions of heating rate c and number of rapid recurrent annealings N have been presented, and are used to explain the mechanism of effective Faraday angle increase and grain size decrease, suggesting that glass/A1/BiGaDyIG films are promising candidates for blue light magneto-optical recording disks.
Magneto-optical properties, Garnet films, Rapid thermal annealing, Crystallization
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