Session 1A4a AC Transport, Impedance Spectra, Magnetoimpedance

Transcription

1 Session 1A4a AC Transport, Impedance Spectra, Magnetoimpedance Magneto-impedance of [Co 40Fe 40B 20/Cu] Multilayer Films S. U. Jen, T. Y. Chou, C. K. Lo, The Phenomenon of Positive Magnetoimpedance in La 0.75Sr 0.25MnO 3 PLD Film Yifei Wang, Hua Liu, Jifan Hu, Magnetoimpedance in Perovskite La 0.7Sr 0.3MnO 3 Ceramics Hua Liu, Qingfang Huang, Jifan Hu, Investigation of the Electrical Properties of BCN-codoped TiO 2 Thin Film Using Impedance Spectroscopy Ling Zhang, Yongfang Zhang, Liangguo Yan, Fang He, Impedance Spectroscopy Study on the Bulk of TiO 2 Ling Zhang, Yongfang Zhang, Liangguo Yan, Fang He, Giant Magnetoimpedance in Nanocrystalline Fe-Zr-B-Cu Ribbon Ling Zhang, Yongfang Zhang, Liangguo Yan, Fang He,

2 42 Progress In Electromagnetics Research Symposium Abstracts, Suzhou, China, September 12 16, 2011 Magneto-impedance of [Co 40 Fe 40 B 20 /Cu] Multilayer Films S. U. Jen 1, T. Y. Chou 1, and C. K. Lo 2 1 Institute of Physics, Academia Sinica, Taipei 11529, Taiwan, R.O.C. 2 Physics Department, National Taiwan Normal University, Taipei 11677, Taiwan, R.O.C. Abstract [Co 40 Fe 40 B 20 (20-z)/Cu(z)] 5 multilayer films, with z = 0 6 nm, were deposited on glass substrates by the magnetron sputtering method at room temperature. During the filmdeposition period, a dc magnetic field, h = 40 Oe, was applied to introduce an easy axis for each film sample. Cross-section transmission electron microscope (X-TEM) photos showed that there are sharp interfaces between neighboring layers. Ferromagnetic resonance (FMR), magnetoimpedance (MI), electrical resistivity (ρ), and magnetic hysteresis loops (MHL) of these films were studied. From MHL and ρ measurements, we obtain saturation magnetization 4πM s = KG, the anisotropy field H k = KG, and ρ = µω-cm. From FMR, we can determine the uniform Kittel-mode-resonance frequency f F MRK = MHz. In the h L case, L is length of the film, MI spectra show the uniform Killel-mode-resonance (UKR) at f 0 = 2081 MHz and the non-uniform Walker-mode-resonance (NWR) at f n, where n = 1, 2, 3, and 4. In the h w case, where w is width of the film, MI spectra show UKR at F 0 = 2431 MHz and NWR at F n. We find f 0 and F 0 are shifted from f F MRK, respectively, and within errors f n = F n. The in-plane spin waves are responsible for those relative shifts.

3 Progress In Electromagnetics Research Symposium Abstracts, Suzhou, China, September 12 16, The Phenomenon of Positive Magnetoimpedance in La 0.75 Sr 0.25 MnO 3 PLD Film Yifei Wang, Hua Liu, and Jifan Hu School of Physics, State Key Laboratory for Crystal Materials Shandong University, Jinan , China Abstract In the present work, La 0.75 Sr 0.25 MnO 3 polycrystalline film was grown on Si (1 0 0) substrate by pulsed laser deposition. Negative magnetoimpedance Z/Z 0 = 2.64% was obtained under a low field of 500 Oe for the film with an 800 C annealing. For the film with a liquid nitrogen treatment after an 800 C annealing, a positive magnetoimpedance occurs at 10 MHz. The peak value of Z/Z 0 is 48.1% under 200 Oe. We suggested that the negative magnetoimpedance for the film with 800 C annealing is connected with a decrease of permeability induced by DC low fields, whereas the positive magnetoimpedance for the film with liquid-nitrogen treatment was connected with an increase of permeability with field, due to the existence of transverse anisotropy developed in the film during the liquid-nitrogen treatment process. With Machado-Rezende model on magnetic domain motion, we calculated the field dependence of transverse susceptibility χ. When a transverse anisotropy field H A exists, the transverse susceptibility χ should have a peak at a field H = H A.

4 44 Progress In Electromagnetics Research Symposium Abstracts, Suzhou, China, September 12 16, 2011 Magnetoimpedance in Perovskite La 0.7 Sr 0.3 MnO 3 Ceramics Hua Liu, Qingfang Huang, and Jifan Hu State Key Laboratory for Crystal Materials, School of Physics Shandong University, Jinan , China Abstract The La 0.7 Sr 0.3 MnO 3 manganite prepared by sintering method exhibits a giant magnetoimpedance. Its AC magnetoresistance R/R 0 could reach 9.53%, magnetoimpedance Z/Z is 3.05% at 200 khz under a low field of 1.8 koe at room temperature, which is more sensitive than its dc colossal magnetoresistance. With an increase of ac frequency, there is a maximum of the GMI effects. To investigate the intrinsic origin of the GMI effect, electrodynamics theory was used to simulate the frequency dependence of magnetoimpedance effect. The influences of frequency, permeability and sample thickness upon the effect of giant magnetoimpedance were investigated.

5 Progress In Electromagnetics Research Symposium Abstracts, Suzhou, China, September 12 16, Investigation of the Electrical Properties of BCN-codoped TiO 2 Thin Film Using Impedance Spectroscopy Ling Zhang, Yongfang Zhang, Liangguo Yan, and Fang He School of Resources and Environment, University of Jinan, Jinan , China Abstract Titanium dioxide has attracted much attention in the past decades. When it was doped by some elements, such as C, N, P, S and B, the conductibility will be obviously changed. In this work, the BCN-doped TiO 2 by nanostructured films was fabricated by co-deposit method. The structure was studied by X-ray diffraction measurement. The microstructure was observed by FE-SEM and XPS. The investigation of ac impedance spectra for BCN-doped TiO 2 thin film was performed. The grain resistance, resistance of grain boundary, and the capacitance in the film were determined from impedance technique.

6 46 Progress In Electromagnetics Research Symposium Abstracts, Suzhou, China, September 12 16, 2011 Impedance Spectroscopy Study on the Bulk of TiO 2 Ling Zhang, Yongfang Zhang, Liangguo Yan, and Fang He School of Resources and Environment, University of Jinan, Jinan , China Abstract Titanium dioxide has attracted much attention in the past decades. It was extensively used in environmental interest in dye-sensitized solar cells and gas-sensing devices. Impedance spectroscopy is a very useful and important technique due to the possibility of using this method for discriminating between grain boundary capacitance (C gb ) and grain boundary resistance (R gb ) contributions. In our work, the bulk of the TiO 2 was prepared by sol-gel method. The structure was studied by X-ray diffraction measurement. The microstructure was observed by FE-SEM and thermal analysis (TG/DTA). The impedance Spectroscopy was investigated.

7 Progress In Electromagnetics Research Symposium Abstracts, Suzhou, China, September 12 16, Giant Magnetoimpedance in Nanocrystalline Fe-Zr-B-Cu Ribbon Ling Zhang, Yongfang Zhang, Liangguo Yan, and Fang He School of Resources and Environment, University of Jinan, Jinan , China Abstract The Fe-Zr-B-Cu ribbon was prepared by melt-spun technique. The ribbons were annealed at different temperature. The structure of Fe-Zr-B-Cu ribbon was studied by X-ray diffraction measurement. The α-fe nanocrystals occur. The magnetoimpedance was observed in nanocrystalline Fe-Zr-B-Cu ribbons.

8 48 Progress In Electromagnetics Research Symposium Abstracts, Suzhou, China, September 12 16, 2011