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The influence of the nonmagnetic metal spacer Bi,Ag and Cu on the properties of the multilayer films

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Chinese Science Bulletin 2006年第18期51卷 2183-2188页

作者： LI Minghua yu guanghua ZHU Fengwu LAI Wuyan College of Mechanical Engineering. South China University of Technology Guangzhou 510640 China Department of Materials Physics University of Science and Technology Beijing Beijing 100083 China Institute of Physics Chinese Academy China

Ta/NiFe/Bi(Ag, Cu)/FeMn/Ta and Ta/ NiFeⅠ /FeMn/Bi(Ag, Cu)/NiFeⅡ/Ta films were prepared by magnetic sputtering. The texture of films was examined by X-ray diffraction (XRD). The depend-ence of the Hex1 between NiFeⅠ/FeMn films and the Hex2 between FeMn/NiFeⅡ on the Bi, Ag and Cu thickness was studied in Ta/NiFeⅠ/FeMn/Bi(Ag, Cu)/ NiFeⅡ/Ta. The experimental results show that the He1 ranged from 130 to 140 Oe with an increase in the nonmagnetic metal spacer thickness. The Hex2 de-creased dramatically and became flat finally with the increase of the Bi, Ag and Cu thickness. XPS results show that Bi, Ag and Cu atoms do not stay entirely at the interface of FeMn/NiFeⅡ film; they are at least partly segregated to the surface of NiFe film. The more Bi, Ag and Cu atoms are deposited, the more they are segregated at the NiFe layer.

关键词： NiFe/FeMn 无磁性垫片交换耦合晶格匹配表面偏析多层膜

Magnetic property and interface structure of Ta/NiO/NiFe/Ta

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Chinese Science Bulletin 2001年第5期46卷 438-440页

作者： yu guanghua CHAI Chunlin ZHU Fengwu XIAO Jimei Department of Materials physics University of Science and TechnologyBeijing 100083China Institute of Semiconductors Chinese Academy of SciencesBeijing 100083China

Ta/NiO/NiFe/Ta multilayers, utilizing Ta as buffer layer, were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field between NiO and NiFe reached a maximum value of 9.6 ×103 A/m at a NiO film thickness of 50 nm. The composition and chemical states at interface region of Ta/NiO/Ta were studied by using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that there is an 'intermixing layer' at the Ta/NiO (and NiO/Ta) interface due to a thermodynamically favorable reaction 2Ta + 5NiO = 5Ni + Ta2O5. This interface reaction has a great effect on exchange coupling. The thickness of Ni+NiO estimated by XPS depth-profiles is about 8-10 nm.

关键词： NiO interface reaction X-ray photoelectron spectros-copy exchange coupling.

Perpendicular exchange bias of (Pt/Co)_n/FeMn multilayers

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Journal of University of Science and Technology Beijing 2007年第6期14卷 543-546页

作者： Zhonghai Zhai Yang liu Jiao Teng Baohe Li guanghua yu Fengwu Zhu Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China College of Science Shenyang Jianzhu University Shenyang 110168 China Department of Mathematics and Physics Beijing Technology and Business University Beijing 100037 China

（Pt/Co）n/FeMn multilayers with perpendicular anisotropy （PA） were prepared by magnetron sputtering with Pt as the buffer layer and the capping layer. The dependence of perpendicular exchange bias （PEB）, Hex, on the thickness of the FeMn anfiferromagnet （AFM） layer is similar to that of in-plane exchange bias. The value of Hex for the （Pt/Co）3/FeMn multilayer reaches 22.3 kA/m. A thin Pt spacer was inserted between the Co/FeMn interface to enhance PEB. The PEB reaches the largest at 39.8 kA/m when the thickness of the Pt spacer is 0.4 nm.

关键词： exchange bias perpendicular anisotropy texture multilayers

Effect of Cu surface segregation on the exchange coupling field of NiFe/FeMn bilayers

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Chinese Science Bulletin 2001年第22期46卷 1934-1936页

作者： LI Minghua yu guanghua ZHU Fengwu JIANG Hongwei LAI Wuyan Department of Materials Physics Beijing University of Science and TechnologyBeijing 100083China Institute of Physics Chinese Academy of SciencesBeijing 100080China

The NiFe/FeMn bilayers with different buffer layers (Ta or Ta/Cu) were prepared by magnetron sputtering. Results show that the exchange coupling field of NiFe/FeMn fllms with Ta buffer is higher than that of the films with Ta/ Cu buffer. We analysed the reasons by investigating the crystallographic texture, surface roughness and surface segregation of both fllms, respectively. We found that the decrease of the exchange coupling fields of NiFe/FeMn fllms with Ta/ Cu buffer layers was mainly caused by the Cu surface segregation on NiFe surface.

关键词： NiFe/FeMn exchange coupling field texture surface roughness surface segregation.

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基于深度学习的红外图像超分辨率重建方法

激光杂志 2024年第1期45卷 142-147页

作者：李岩杨得成于光华高爽刘禹彤翟茁张宝金黑河学院黑龙江黑河164300

为了提高红外图像的超分辨率重建效果,提出基于深度学习的红外图像超分辨率重建方法。利用红外图像的反射特性与红外辐射特性建立红外图像的显著性区域检测模型;通过可见光与近红外图像之间样貌差异度水平检测图像的边缘轮廓特征,提取... 详细信息

为了提高红外图像的超分辨率重建效果,提出基于深度学习的红外图像超分辨率重建方法。利用红外图像的反射特性与红外辐射特性建立红外图像的显著性区域检测模型;通过可见光与近红外图像之间样貌差异度水平检测图像的边缘轮廓特征,提取可见光与近红外光融合性特征参数;根据融合层次不同对图像信号级、像素级、特征级、决策级四个维度进行重建,提取图像的边缘、形状、纹理特征;根据特征分布的噪声水平与配准质量,采用深度学习算法实现对红外图像超分辨率重建。仿真测试结果得出,该方法进行红外图像重建的显著性特征检测能力较强,重建后将图像分辨率提升到1280×960 PPI,模板匹配准确率为49.4%,峰值信噪比PSNR值高于36.34 dB,结构相似度SSIM值高于0.972,重建效果较好,更适合用于特定场景下的红外图像目标特征识别。

关键词：深度学习红外图像超分辨率重建可见光近红外光

Investigation on high magnetoresistance Ni_(0.81)Fe_(0.19) films grown on (Ni_(0.81)Fe_(0.19))_(1-x)Cr_(x) underlayers

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Chinese Science Bulletin 2003年第11期48卷 1087-1089页

作者： LI Haifeng MA Jidong yu guanghua LONG Shibin ZHAO Hongchen ZHU Fengwu Department of Material Physics and Chemistry University of Science and Technology Beijing 100083 China

We have fabricated Ni0.81Fe0.19 films with (Ni0.81Fe0.19)1-xCrx films as underlayers by dc magnetron sputtering, the results show that larger anisotropic magnetoresistance (△R/R) values of Ni0.81Fe0.19 films are observed using the underlayers with Cr concentration of ~36 at.% at an optimum underlayer thickness of ~4.4 nm, the maximum AMR value is 3.35%. The results of atomic force microscope (AFM) and X-ray diffraction (XRD) show that the △R/R enhancement is attributed to the formation of large average grain size and the strong(111) texture in the Ni0.81Fe0.19 films.

关键词：磁致电阻薄膜生长衬底直流磁电管各向异性 Ni0.18Fe0.19

DENSITY FUNCTIONAL FOR STRUCTURES OF COLLOIDS CONFINED IN A SLIT-LIKE PORE

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China Particuology 2005年第5期3卷 265-270页

作者： Fengqi You Sheng Fu Yangxin yu guanghua Gao State Key Laboratory of Chemical Engineering Department of Chemical Engineering Tsinghua University Beijing 100084 P. R. China

A density functional theory is applied to calculating the local density profiles of colloids confined in a slit-like pore as well as the radial distribution functions of bulk colloids. The interaction between the colloidal particles is described using a hard-core yukawa model. The excess Helmholtz energy functional is a combination of the modified fundamental measure theory of yu and Wu （2002） for the hard-core contribution and a corrected mean-field theory for the attractive contribution. Comparison with the results from the Monte Carlo simulations shows that the corrected theory improves the density profiles of colloids in the vicinity of contact over the original mean-field theory. Both the present corrected theory and simulations suggest that there are depletion and desorption for the colloid with strong attraction between particles at low temperature.

关键词： colloid slit-like pore inhomogeneous fluid fundamental theory yukawa model

Chemical states of the atoms in magnetic multilayers Ta/NiO_x/Ni_(81)Fe_(19)/Ta and Co/AlO_x/Co

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Chinese Science Bulletin 2002年第4期47卷 276-279页

作者： yu guanghua, ZHU Fengwu & CHAI ChunlinDepartment of Materials Physics, University of Science and Technology, Beijing 100083, China Department of Materials Physics University of Science and Technology Beijing China

Ta/NiOx/Ni81Fe19/Ta and Co/AlOx/Co multilay-ers were prepared by rf reactive and dc magnetron sputter-ing. The exchange coupling field (Hex) and the coercivity (Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that when the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is +2. At this point, NiOx is anti-ferromagnetic NiO and the corresponding Hex is the largest. As the ratio of Ar/O2 deviates from 7, the Hex will decrease due to the presence of magnetic impurities such as Ni+3 or metallic Ni at the interface region of NiOx/NiFe, while the Hc will increase due to the metallic Ni. Al layers in Co/AlOx/Co multilayers were also studied by angle-resolved XPS. Our finding is

关键词： NiOx/NiFe exchange coupling Co/AlOx/Co X-ray pho-toelectron spectroscopy (XPS) chemical states.

Magnetic properties and structure of very thin permalloy films

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Journal of University of Science and Technology Beijing 2004年第3期11卷 225-229页

作者： guanghua yu Haifeng Li Tao Yang Fengwu Zhu Materials Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

In order to study the magnetic properties and structure of very thinpermalloy films, Ni_(81)Fe_(19) films of 12 nm in thickness were prepared by different instrumentsat an ultrahigh base vacuum and a lower base vacuum. The anisotropic magnetoresistance coefficients(ΔR/R) of Ni_(81)Fe_(19) (12 nm) films reached 1.6 % and 0.6 %, and the coercivities were 127 and334 A/m, respectively. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were usedto study the structure and surface chemical state. The experimental results show that the filmsprepared at the ultrahigh base vacuum have a smoother surface, a bigger grain size and a denserstructure with fewer defects than those prepared at the lower base vacuum.

关键词： NiFe film anisotropic magnetoresistance (AMR) coercivity structure