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【期刊论文】Effect of thermal stability on magnetoresistance in NiO spin valve
吴小山, A. M. Zhang, X. S. Wu, a) L. Sun, W. T. Sheng, B. You, J. Du, M. Lu, A. Hu, and S. S. Jiang
J. Appl. Phys., Vol. 95, No.11, Part 2, 1 June 2004,-0001,():
-1年11月30日
The interface structure and magnetoresistance (MR) for the single spin valve (SV) of Co/Cu/Co structure with a NiO layer at the top or under the bottom were investigated. Glancing incident x-ray reflectivity and x-ray diffuse scatter studies show that the interface roughness of NiO on Co is much larger than that of Co on NiO. The large roughness may be one of the main factors of suppressing spin reflectivity. The interface between NiO and Co becomes more flat after annealing. Different temperature dependence of MR was observed for the top and the bottom SV. We attribute the above phenomena to the competition between the roughness and the exchange effects of the NiO/Co interface.
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【期刊论文】Coexistence of superconductivity and antiferromagnetism in the La1-xPrxBa2Cu3O7 system
吴小山, H. M. Luo, a) S. Y. Ding, and X. S. Wu
J. Appl. Phys., Vol. 89, No.11, 1 June 2001,-0001,():
-1年11月30日
Structural, magnetic, and calorimetric properties are reported for the La12xPrxBa2Cu3O7 solid olution. The structure remains orthorhombic with lattice parameter increases from a50.3872, b 50.3927, and c51.1709nm for PrBa2Cu3O7 to a50.3903, b50.3944, and c51.1801nm for LaBa2Cu3O7. Substitution of Pr for La depresses Tc from 90 to 52K for La0.5Pr0.5Ba2Cu3O7, which was reported to be a nonsuperconductor. The Pr antiferromagnetic ordering temperature TN decreases monotonically from 18K for PrBa2Cu3O7 to 6K for La0.8Pr0.2Ba2Cu3O7. Thus there is a large range of coexistence of superconductivity and antiferromagnetism for 0.2<x<0.5. The superconductivity and anomalous Pr ordering will be discussed with the R12xPrxBa2Cu3O7 systems R5Y, Nd-Lu.
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【期刊论文】Microstructures and resistivity of cuprate' manganite bilayer deposited on SrTiO3 substrate
吴小山, W. S. Tan, a) X. S. Wu, J. Du, J. S. Liu, A. Hu, and S. S. JiangJ. Wang, Z. H. Wu, W. L. Zheng, and Q. J. Jia J. Gao
J. Appl. Phys., Vol. 93, No.10, Parts 2 & 3, 15 May 2003,-0001,():
-1年11月30日
Thin YBa2Cu3O7-d/La0.67Ca0.33MnO3 (YBCO/LCMO) films were grown on SrTiO3 (STO) substrates by magnetron sputtering technique. The microstructures of the bilayers were characterized and a standard four-probe technique was applied to measure the resistivity of the samples. The interdiffusions at the YBCO/LCMO and LCMO/STO interfaces formed two transient layers with the thickness of about 3 and 2nm, respectively. All the bilayers were well textured along the c axis. At low temperature, the superconductivity can only be observed when the thickness of YBCO is more than 25nm. When the ickness of YBCO is less than 8nm, the bilayers show only ferromagnetism. The superconductivity and ferromagnetism perhaps coexist in the bilayer with the YBCO thickness of 12.5nm. These interesting properties are related to the interaction between spin polarized electrons in the manganites and the cooper pairs in the cuprates.
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【期刊论文】Soft X-ray reflectivity for YBa2Cu3O7−δand La2/3Ca1/3MnO3 films
吴小山, X. S. Wu a, S. S. Jiang a, *, M. Q. Cui b, P. P. Zhu b, J. Gao c
Journal of Electron Spectroscopy and Related Phenomena 144-147(2005)471-474,-0001,():
-1年11月30日
The film of La2/3Ca1/3MnO3 (LCMO), YBa2Cu3O7−δ (YBCO) and YBCO/LCMO bi-layer were prepared by rf off-axis magnetic sputtering technique on SrTiO3 (STO) substrate. The structures, including the surface and interfacial morphology, the interfacial diffusion and so on, have been characterized by X-ray diffraction (XRD), auger electronic energy spectroscopy (AES) and atomic force microscopy (AFM). Through a 50-200eV energy range, a single layer of YBCO shows a very small reflectance (<2%), while a single layer of LCMO shows a higher reflectance of about 25% at the energy of about 75eV, which is much higher than that of metal W. Even higher reflectance (>50%) at about 75eV has been observed in the LCMO/YBCO bi-layers.
Bi-layers, Interdiffusion, Reflectivity
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【期刊论文】A neutron powder diffraction study of the superconductor Hg-1223 via Pb substitution
吴小山, X S Wu y, C Gou z, D F Chen z, H M Shao y and S S Jiang y
Condens. Matter 8(1996)3647-3652. Printed in the UK,-0001,():
-1年11月30日
The mercury-based superconductor Hg-1223 with Pb substituted for Hg has a transition temperature (T RD0 c, the zero-resistance temperature, 135K; T diac, the diamagnetic onset temperature, D 143K) higher than that for pure Hg-1223 compound. The structure of this Pb-doped sample has been nvestigated via neutron powder diffraction. Some selected bond distances are compared to those of Pb-free Hg-1223 cuprate. The contents of Pb and oxygen have been refined. The estimated valence of copper is about 2. 30, which is consistent with that for YBCO superconductor.
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