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The effect of multilayer structure on magnetic properties of FePt thin films

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Acta Metallurgica Sinica(English Letters) 2009年第1期22卷 22-26页

作者： Kaifeng DONG Xiaofei YANG Junbing YAN weiming cheng Xiaomin cheng Department of Electronic Science ＆： Technology Huazhong University of Science ＆ TechnologyWuhan 430074 China

The Fe/Pt multilayer films with different structures were deposited by RF magnetron sputtering on glass substrates, and the L10-FePt films were obtained after the asdeposited samples were subjected to vacuum annealing at various temperatures. Results show that the Fe/Pt multilayer structure can effectively reduce the ordering temperature of FePt film, and the in-plane coercivity of [Fe （5.2 nm）/Pt （5.2 nm）]7 multilayers can reach 161.2 kA/m after annealed at 350℃ for 30 min. When Fe and Pt layer thickness is equal, the coercivity of the film is the largest. On the other hand, the different Fe-Pt crystalline phases such as Fe3Pt and FePt3 phases are formed after annealing when the thickness ratio of Fe/Pt deviates from 1 after annealing. When Fe and Pt have the same thickness, the thinner single layer gets the lower ordering temperature and the larger coercivity.

关键词： L10-FePt thin films Multilayer structure Coercivity Ordering temperature

Effect of Ni doping on the microstructure and magnetic properties of FePt films

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Rare Metals 2009年第3期28卷 257-260页

作者： DONG Kaifeng cheng Xiaomin YAN Junbing cheng weiming LI Peng YANG Xiaofei Department of Electronic Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

FePtNi films with different Ni contents were deposited on glass substrates by RF magnetron sputtering, and the L10-FePtNi films were obtained after the asdeposited samples were subjected to vacuum annealing. The magnetic properties, structures, and orientations of the L10-FePt films with Ni doping were studied. The results show that with increasing Ni content, the （001） peak position of the FePtNi films shifts to a higher angle in comparison with FePt, which suggests that there is partial Ni substitution in the L10 lattice. The perpendicular coercivity decreases from 661 to 142 kA/m and magnetization decreases from 512 to 433 kA/m with increasing Ni content. In comparison with FePt films, the FePtNi films can effectively reduce the Curie temperature, which makes FePtNi films promising media candidates in thermally assisted recording （TAR）.

关键词： FePtNi films Curie temperature magnetization coercivity

Morphological differentiation characteristics and classification criteria of lunar surface relief amplitude

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Journal of Geographical Sciences 2022年第11期32卷 2365-2378页

作者： DENG Jiayin cheng weiming LIU Qiangyi JIAO Yimeng LIU Jianzhong State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China CAS Center for Excellence in Comparative Planetology Hefei 230052China Lunar and Planetary Science Research Center Institute of GeochemistryCASGuiyang 550002China

Lunar landforms are the results of geological and geomorphic processes on the lunar *** is very important to identify the types of lunar *** is the scientific study of the origin and evolution of morphological landforms on planetary *** and relief amplitude are the most commonly used geomorphic indices in geomorphological classification *** studies have determined the elevation classification criteria of the lunar *** this paper,we focus on the classification criteria of the topographic relief amplitude of the lunar *** estimate the optimal window for calculating the relief amplitude of the lunar surface,we use the mean change-point method based on LOLA(Lunar Orbiter Laser Altimeter)Digital Elevation Model(DEM)data and SLDEM2015 DEM data combining observations from LOLA and SELenological and Engineering Explorer Terrain Camera(SELENE TC).The classification criterion of the lunar surface relief amplitude is then determined according to the statistical analysis of basic lunar *** the topographic relief amplitudes of 100 m,200 m,300 m,700 m,1500 m and 2500 m as thresholds,the lunar surface is divided into seven geomorphic types,including minor microrelief plains(<100 m),minor microrelief platforms[100 m,200 m),microrelief landforms[200 m,300 m),small relief landforms[300 m,700 m),medium relief landforms[700 m,1500 m),large relief landforms[1500 m,2500 m)and extremely large relief landforms(≥2500 m).The minor microrelief plains are mainly distributed in the maria and the basalt filled floors of craters and basins,while the minor microrelief platforms are mainly in the transition regions between the maria and *** microrelief landforms are mainly located in regions with relatively high topography,such as wrinkle ridges and sinuous rilles in the *** small relief landforms are mainly scattered in the central peak and floor fractures of *** medium relief landforms are mai

关键词： lunar geomorphological classification schemes morphometric features lunar relief amplitude characteristics analysis classification criterion

Mitigating set-stuck failure in 3D phase change memory: substituting square pulses with surge pulses

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Science China(Information Sciences) 2024年第5期67卷 295-301页

作者： Ninghua LI Wang CAI Jun XIANG Hao TONG weiming cheng Xiangshui MIAO School of Integrated Circuits Huazhong University of Science and Technology Hubei Yangtze Memory Laboratories Hubei Institute of Measurement and Testing Technology

In the devices that integrate phase change memory(PCM) and ovonic threshold switching(OTS),the OTS threshold voltage often surpasses the RESET operation voltage of PCM. The conventional application of square pulses hinders the successful completion of the SET operation in these integrated devices. To address this challenge, a novel pulse called the surge pulse is introduced, which comprises a high amplitude pulse for OTS activation and a low amplitude pulse for PCM operation. By employing COMSOL simulation,the operational effectiveness of both square pulses and surge pulses is validated. Test results reveal that using a square pulse to operate the integrated device accelerates the occurrence of SET-stuck failure(SSF).In contrast, the surge pulse enables the integrated device to operate for at least 1000 cycles while preserving the essential cyclic characteristics. Additionally, an investigation into the overshoot component of the surge pulse is conducted, revealing that an increase in overshoot amplitude and pulse width also accelerates the emergence of SSF. By applying the theory of ion migration induced by the electric field, the root cause of SSF in integrated devices is explained, and the accuracy of the theory is validated through the application of a reverse pulse. In summary, this study elucidates the rationality of replacing the square pulse with a surge pulse, presenting a superior approach for operating PCM and OTS integrated devices.

关键词： surge pulse phase change memory (PCM) integration SET-stuck failure (SSF) square pulse

Climate effects on an inland alpine lake in Xinjiang, China over the past 40 years

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Journal of Arid Land 2013年第2期5卷 188-198页

作者： HuiXia CHAI weiming cheng chengHu ZHOU ShangMin ZHAO HaiJiang LIU State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Department of Surveying Mapping College of Mining Technology Taiyuan University of Technology China National Environmental Monitoring Center

Inland lakes are important water resources in arid and semiarid regions. Understanding climate effects on these lakes is critical to accurately evaluate the dynamic changes of water resources. This study focused on the changes in Sayram Lake of Xinjiang, China, and addressed the effects of climate fluctuations on the inland lake based on long-term sequenced remote sensing images and meteorological data from the past 40 years. A geo- graphic information system （GIS） method was used to obtain the hypsometry of the basin area of Sayram Lake, and estimation methods for evaporation from rising temperature and water levels from increasing precipitation were proposed. Results showed that：（1）Areal values of Sayram Lake have increased over the past 40 years. （2） Both temperature and precipitation have increased with average increases of more than 1.8~C and 82 mm, respectively. Variation of the water levels in the lake was consistent with local climate changes, and the areal values show linear relationships with local temperature and precipitation data. （3） According to the hypsometry data of the basin area, the estimated lake water levels increased by 2.8 m, and the water volume increased by 12.9×108 m3 over the past 40 years. The increasing area of Sayram Lake correlated with local and regional climatic changes because it is hardly affected by human activities.

关键词： Sayram Lake climate change water body extraction areal variation inland alpine lake

Automatic extraction of lunar impact craters from Chang'E-1 satellite photographs

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Science China(Physics,Mechanics & Astronomy) 2012年第1期55卷 162-169页

作者： WAN Cong cheng weiming ZHOU ZengPo ZHAO ShangMin XIA Yao State Key Laboratory of Resources and Environmental Information Systems Institute of Geographic and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China

The distribution characteristics of the impact craters can provide a large amount of information on impact history and the lunar evolution process. In this research, based on the digital elevation model （DEM） data originating from Change＇E-1 CCD stereo camera, three automatic extraction methods for the impact craters are implemented in two research areas： direct extraction from flooded DEM data （the Flooded method）, object-oriented extraction from DEM data by using ENVI ZOOM function （the Object-Oriented method） and novel object-oriented extraction from flooded DEM data （the Flooded Object-Oriented method）. Accuracy assessment, extracted degree computation, cumulative frequency analysis, shape and age analysis of the extracted craters combined display the following results. （1） The Flooded Object-Oriented method yields better accuracy than the other two methods in the two research areas; the extraction result of the Flooded method offers the similar accuracy to that of the Object-Oriented method. （2） The cumulative frequency curves for the extracted craters and the confirmed craters share a simi- lar change trajectory. （3） The number of the impact craters extracted by the three methods in the Imbrian period is the largest and is of various types; as to their age earlier than lmbrain, it is difficult to extract because they could have been destroyed.

关键词： automatic extraction lunar impact craters Object-Oriented method accuracy assessment cumulative frequencyanalysis Chang'E-1 data

Growth of the Sayram Lake and retreat of its water-supplying glaciers in the Tianshan Mountains from 1972 to 2011

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Journal of Arid Land 2016年第1期8卷 13-22页

作者： cheng weiming WANG Nan ZHAO Shangmin FANG Yue ZHAO Min State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Surveying and Mapping College of Mining Engineering Taiyuan University of Technology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences

Inland lakes and alpine glaciers are important constituents of water resources in arid and semiarid regions. Understanding their variations is critical for both an accurate evaluation of the dynamic changes of water resources and the retrieval of climatic information. On the basis of earlier researches, this study investigated the growth of the Sayram Lake and the retreat of its water-supplying glaciers in the Tianshan Mountains using long-term sequenced remote sensing images. Our results show that over the past 40 years, the surface area and the water level of the lake has increased by 12.0±0.3 km2 and 2.8 m, respectively, and the area of its water-supplying glaciers has decreased continuously since the early 1970s with a total reduction of about–2.13±0.03 km2. Our study has indicative significance to the research of regional climate change.

关键词： Sayram Lake inland lake areal variation water level change glacial retreat

Effects of Nd Substitution on Magnetic and Magneto-optical Properties of TbCo/Cr Films

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 166-168页

作者： cheng weiming LI Zuoyi YANG Xiaofei JIN Fang HUANG Zhixin LIN Gengqi cheng Xiaomin Department of Electronic Science and Technology Huazhong University of Science and Technology Wuhan 430074 China Department of Physics Huazhong Normal University Wuhan 430079 China

NdTbCo/Cr amorphous films with high perpendicular magnetic anisotropy were prepared onto glass substrates by rf magnetron sputtering. The effects of Nd substitution on the magnetic and magneto-optical properties of TbCo/Cr films were investigated. It was found that partial Tb substitution by Nd would increase the saturation magnetization and the Kerr rotation angle, change the temperature dependence of magneto-optical characteristics. These results can be explained by the ferrimagnetic structure of the rare earth-transition metal alloy. When the magnetic layer composition was （Nd0.265Tb0.735）31Co69, a saturation magnetization of 247 emu/cm^3 and a coercivity of 3.8 kOe at room temperature could be obtained.

关键词： NdTbCo/Cr films perpendicular magnetic anisotropy saturation magnetization Kerr rotation angle ferrimagnetic structure

On the use of explainable AI for susceptibility modeling:Examining the spatial pattern of SHAP values

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Geoscience Frontiers 2024年第4期15卷 14-27页

作者： Nan Wang Hongyan Zhang Ashok Dahal weiming cheng Min Zhao Luigi Lombardo Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains Ministry of EducationSchool of Geographical SciencesNortheast Normal UniversityChangchun 130024China State Key Laboratory of Resources and Environmental Information Systems Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Twente Faculty of Geo-Information Science and Earth Observation(ITC)PO Box 217EnschedeAE 7500Netherlands University of Chinese Academy of Sciences Beijing 100049China Jiangsu Center for Collaborative Innovation in Geographic Information Resource Development and Application Nanjing 210023China Collaborative Innovation Center of South China Sea Studies Nanjing 210093China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China Key Laboratory of Environmental Change and Natural Disaster Beijing Normal UniversityBeijing 100875China Center for Geodata and Analysis Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China

Hydro-morphological processes(HMP,any natural phenomenon contained within the spectrum defined between debris flows and flash floods)are globally occurring natural hazards which pose great threats to our society,leading to fatalities and economical *** this reason,understanding the dynamics behind HMPs is needed to aid in hazard and risk *** this work,we take advantage of an explainable deep learning model to extract global and local interpretations of the HMP occurrences across the whole Chinese *** use a deep neural network architecture and interpret the model results through the spatial pattern of SHAP *** doing so,we can understand the model prediction on a hierarchical basis,looking at how the predictor set controls the overall susceptibility as well as doing the same at the level of the single mapping *** model accurately predicts HMP occurrences with AUC values measured in a ten-fold cross-validation ranging between 0.83 and *** level of predictive performance attests for an excellent prediction *** main difference with respect to traditional statistical tools is that the latter usually lead to a clear interpretation at the expense of high performance,which is otherwise reached via machine/deep learning solutions,though at the expense of *** recent development of explainable Al is the key to combine both *** this work,we explore this combination in the context of HMP susceptibility ***,we demonstrate the extent to which one can enter a new level of data-driven interpretation,supporting the decision-making process behind disaster risk mitigation and prevention actions.

关键词： Hydro-morphological processes SHAP maps Explainable AI China