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Probing the magnetization switching with in-plane magnetic anisotropy through field-modified magnetoresistance measurement

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Chinese Physics B 2022年第1期31卷 101-106页

作者：郝润润张昆李迎港曹强张学莹朱大鹏赵巍胜 Fert Beijing Institute MIIT Key Laboratory of SpintronicsSchool of Integrated Circuit Science and EngineeringBeihang UniversityBeijing 100191China Beihang-Goertek Joint Microelectronics Institute Qingdao Research InstituteBeihang UniversityQingdao 266000China Spintronics Institute University of JinanJinan 250022China truth instruments co.ltd. Qingdao 266000Chin

Effective probing current-induced magnetization switching is highly required in the study of emerging spin-orbit torque(SOT)effect.However,the measurement of in-plane magnetization switching typically relies on the giant/tunneling magnetoresistance measurement in a spin valve structure calling for complicated fabrication process,or the non-electric approach of Kerr imaging technique.Here,we present a reliable and convenient method to electrically probe the SOT-induced in-plane magnetization switching in a simple Hall bar device through analyzing the MR signal modified by a magnetic field.In this case,the symmetry of MR is broken,resulting in a resistance difference for opposite magnetization orientations.Moreover,the feasibility of our method is widely evidenced in heavy metal/ferromagnet(Pt/Ni_(20)Fe_(80) and W/co_(20)Fe_(60)B_(20))and the topological insulator/ferromagnet(Bi_(2)Se_(3)/Ni_(20)Fe_(80)).Our work simplifies the characterization process of the in-plane magnetization switching,which can promote the development of SOT-based devices.

关键词： magnetoresistance in-plane magnetization switching electrical detection

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Perpendicular magnetic anisotropy based spintronics devices in Pt/co stacks under different hard and flexible substrates

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Science China(Information Sciences) 2023年第2期66卷 256-266页

作者： Sylvain EIMER Houyi CHENG Jinji LI Xueying ZHANG Chao ZHAO Weisheng ZHAO Hefei Innovation Research Institute Anhui High Reliability Chips Engineering LaboratoryBeihang University Fert Beijing Institute MIIT Key Laboratory of Spintronics School of Integrated Circuit Science and EngineeringBeihang University School of Physics and Quantum Information Research Center Southeast University truth instruments co.ltd. Beihang-Geortek Joint Microelectronics Institute Qingdao Research InstituteBeihang University Beijing Superstring Academy of Memory Technology

The magnetic properties in substrate/Pt/co multilayers, such as perpendicular magnetic anisotropy(PMA), are of particular interest for spintronic devices. In particular, it is important to obtain a strong PMA on the flexible substrate in the field of wearable devices and structural health monitoring.However, the different stacks deposition and regulation conditions on the magnetic properties of the films lack systematic research. Here, we investigate the magnetic properties in Pt/co structures with different hard and flexible substrates, layer thicknesses, and the different deposition temperatures of the buffer layer.We found that the coercive field and magnetodynamic behavior of the films change with these factors. Moreover, depositing the buffer layer under high temperature can effectively adjust the crystalline state of the films, thus affecting the performance of the films. After depositing the buffer layer at 800℃, our films can obtain a better crystalline state and PMA. The measurement results of the magneto-optical Kerr microscope show that the magnetic domain wall motion of the films can be controlled by different substrate and buffer layer conditions. It was expected that ultra-fast magnetic moment switching can be achieved by optimizing the conditions to reduce the power consumption of the device. The experimental results also show that the optimized film conditions can also obtain strong PMA on the flexible substrate. These findings help to understand magnetic properties in these structures and show the promising prospect for wearable devices and other spintronic devices.

关键词： Pt/co stacks perpendicular magnetic anisotropy magnetodynamicbehavior spintronics flexible devices high temperature deposition

Rock joint detection from borehole imaging logs using a convolutional neural networks model

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Journal of Earth Science 2024年

作者： Yunfeng Ge Geng Liu Haiyan Wang Huiming Tang Binbin Zhao Research Institute of Transmission and Transformation Projects China Electric Power Research Institute co. ltd State Grid corporation of China Badong National Observation and Research Station of Geohazards China University of Geosciences Hunan Earthquake Agency Faculty of Engineering China University of Geosciences

To map the rock joints in the underground rock mass， a method was proposed to semi-automatically detect the rock joints from borehole imaging logs using a deep learning algorithm. First， 450 images containing rock joints were selected from borehole ZKZ01 in the Rumei hydropower station. These images were labeled to establish ground truth which was subdivided into training， validation， and testing data. Second， the YOLO v2 model with optimal parameter settings was constructed. Third， the training and validation data were used for model training， while the test data was used to generate the Precision-Recall curve for prediction evaluation. Fourth， the trained model was applied to a new borehole ZKZ02 to verify the feasibility of the model. There were 12 rock joints detected from the selected images in borehole ZKZ02 and four geometric parameters for each rock joint were determined by sinusoidal curve fitting. The average precision of the trained model reached 0.87.

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Panoptic UAV:Panoptic Segmentation of UAV Images for Marine Environment Monitoring

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工程与科学中的计算机建模(英文) 2024年第1期138卷 1001-1014页

作者： Yuling Dou Fengqin Yao Xiandong Wang Liang Qu Long Chen Zhiwei Xu Laihui Ding Leon Bevan Bullock Guoqiang Zhong Shengke Wang School of computer Science and Technology Ocean University of ChinaQingdao266100China North China Sea Environmental Monitoring Center State Oceanic AdministrationQingdao266000China Department of Informatics University of LeicesterLeicesterLE17RHUK Research and Development Department Shandong Willand Intelligent Technology Co.Ltd.Qingdao266102China

UAV marine monitoring plays an essential role in marine environmental protection because of its flexibility and convenience,low cost and convenient maintenance.In marine environmental monitoring,the similarity between objects such as oil spill and sea surface,Spartina alterniflora and algae is high,and the effect of the general segmentation algorithm is poor,which brings new challenges to the segmentation of UAV marine images.Panoramic segmentation can do object detection and semantic segmentation at the same time,which can well solve the polymorphism problem of objects in UAV ocean images.Currently,there are few studies on UAV marine image recognition with panoptic segmentation.In addition,there are no publicly available panoptic segmentation datasets for UAV images.In this work,we collect and annotate UAV images to form a panoptic segmentation UAV dataset named UAV-OUC-SEG and propose a panoptic segmentation method named PanopticUAV.First,to deal with the large intraclass variability in scale,deformable convolution and CBAM attention mechanism are employed in the backbone to obtain more accurate features.Second,due to the complexity and diversity of marine images,boundary masks by the Laplacian operator equation from the ground truth are merged into feature maps to improve boundary segmentation precision.Experiments demonstrate the advantages of PanopticUAV beyond the most other advanced approaches on the UAV-OUC-SEG dataset.

关键词： Panoptic segmentation UAV marine monitoring attention mechanism boundary mask enhancement

The Theory on Thing’s Limits. Part 2: A Brief Analysis of the New Knowledge of Newton’s First Law

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Journal of Electronic & Information Systems 2023年第1期5卷 10-19页

作者： Jian Ding Integrated Electronic Systems Lab co.ltd. JinanShandong250100China

According to the norm of identifying truth in this theory,and Newton’s first law as a basis that can look at the overall situation,and by virtue of the electron storage ring as an experimental fact,it is pointed out:Only in reality can there be inertia.Inertia represents the continuity of the development of things.As the speed gradually approaches the c,the particle’s mass also approaches zero along with its static mass due to the impact of electromagnetic radiation,which is exactly the root where the energy shrinkage effect of high-speed particles comes from,and also the primary factor causing the spectrum redshift.Therefore,the Big Bang theory is wrong.All photons are produced from high-density particles through electromagnetic radiation.Wherever there is fluctuation,there must be mass,and vice versa.This is the correct understanding of“wave-particle duality”.No matter whether the high-speed electrons or the photons produced by them all have different static masses,their charge-mass ratio is always the same physical constant,and not affected by relativistic effects and electromagnetic radiations.This is the true internal mechanism to constitute the uncertainty principle,and conforms to the experimental facts related to it.It can be proved that in a constant magnetic field,the high-speed electron or photon having a relatively large curvature radius has a high moving speed and less mass,energy and wave frequency.Since Einstein used the absolute space-time established by Newton as the criterion and came to the conclusion that the relative space-time was curved,then he should no longer make circular arguments,that was,used the relative space-time as the criterion,to change the unit length and time established by the absolute space-time.

关键词： Mechanics Relativity Electron Photon Electromagnetic radiation Energy shrinkage

Demonstration of a manufacturable SOT-MRAM multiplexer array towards industrial applications

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Journal of Semiconductors 2023年第12期44卷 81-88页

作者： Chuanpeng Jiang Jinhao Li Hongchao Zhang Shiyang Lu Pengbin Li Chao Wang Zhongkui Zhang Zhengyi Hou Xu Liu Jiagao Feng He Zhang Hui Jin Gefei Wang Hongxi Liu Kaihua Cao Zhaohao Wang Weisheng Zhao School of Integrated Circuit Science and Engineering Beihang UniversityBeijing 100191China truth Memory corporation Beijing 100088China

We have successfully demonstrated a 1 Kb spin-orbit torque(SOT)magnetic random-access memory(MRAM)multiplexer(MUX)array with remarkable performance.The 1 Kb MUX array exhibits an in-die function yield of over 99.6%.Additionally,it provides a sufficient readout window,with a TMR/RP_sigma%value of 21.4.Moreover,the SOT magnetic tunnel junctions(MTJs)in the array show write error rates as low as 10^(-6)without any ballooning effects or back-hopping behaviors,ensuring the write stability and reliability.This array achieves write operations in 20 ns and 1.2 V for an industrial-level temperature range from-40 to 125℃.Overall,the demonstrated array shows competitive specifications compared to the state-of-the-art works.Our work paves the way for the industrial-scale production of SOT-MRAM,moving this technology beyond R&D and towards widespread adoption.

关键词： spin-orbit torque MRAM multiplexer array 200 mm-wafer platform stability reliability

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Optimal CNN-based semantic segmentation model of cutting slope images

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Frontiers of Structural and Civil Engineering 2022年第4期16卷 414-433页

作者： Mansheng LIN Shuai TENG Gongfa CHEN Jianbing LV Zhongyu HAO School of Civil and Transportation Engineering Guangdong University of TechnologyGuangzhou 510006China JSTI Group Guangdong Inspection and Certification co.ltd Nanjing 210000China

This paper utilizes three popular semantic segmentation networks,specifically DeepLab v3+,fully convolutional network(FCN),and U-Net to qualitively analyze and identify the key components of cutting slope images in complex scenes and achieve rapid image-based slope detection.The elements of cutting slope images are divided into 7 categories.In order to determine the best algorithm for pixel level classification of cutting slope images,the networks are compared from three aspects:a)different neural networks,b)different feature extractors,and c)2 different optimization algorithms.It is found that DeepLab v3+with Resnet18 and Sgdm performs best,FCN 32s with Sgdm takes the second,and U-Net with Adam ranks third.This paper also analyzes the segmentation strategies of the three networks in terms of feature map visualization.Results show that the contour generated by DeepLab v3+(combined with Resnet18 and Sgdm)is closest to the ground truth,while the resulting contour of U-Net(combined with Adam)is closest to the input images.

关键词： slope damage image recognition semantic segmentation feature map visualizations

From Keeping Harmony with All States To Building a Harmonious World——To have a profound grasp of China's peaceful development strategy from the perspective of history and culture

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Peace 2014年第2期 13-17,24页

作者： Yang Faxi the International Department CPC "Seeking truth" magazine

To objectively and rationally grasp the strategic intent of peaceful development China adheres to is the important foundation and prerequisite to construct a new-type China-U.S.relations among major powers featuring non-confrontation,non-conflict,mutual respect,and win-win cooperation.To achieve the objectiveness and rationality,one must understand China’s historical and cultural traditions,and understand the Chinese pursuit

关键词： grasp cooperation prerequisite pursuit mutual prof

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Tunneling magnetoresistance materials and devices for neuromorphic computing

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Materials Futures 2023年第3期2卷 90-113页

作者： Yuxuan Yao Houyi Cheng Boyu Zhang Jialiang Yin Daoqian Zhu Wenlong Cai Sai Li Weisheng Zhao Fert Beijing Institute MIIT Key Laboratory of SpintronicsSchool of Integrated Circuit Science and EngineeringBeihang UniversityBeijing 100191People’s Republic of China Hefei Innovation Research Institute Anhui High Reliability Chips Engineering LaboratoryBeihang UniversityHefei 230013People’s Republic of China truth Equipment corporation TRECHefei 230013People’s Republic of China Beihang-Geortek Joint Microelectronics Institute Qingdao Research InstituteBeihang UniversityQingdao 266061People’s Republic of China

Artificial intelligence has become indispensable in modern life,but its energy consumption has become a significant concern due to its huge storage and computational demands.Artificial intelligence algorithms are mainly based on deep learning algorithms,relying on the backpropagation of convolutional neural networks or binary neural networks.While these algorithms aim to simulate the learning process of the human brain,their low bio-fidelity and the separation of storage and computing units lead to significant energy consumption.The human brain is a remarkable computing machine with extraordinary capabilities for recognizing and processing complex information while consuming very low power.Tunneling magnetoresistance(TMR)-based devices,namely magnetic tunnel junctions(MTJs),have great advantages in simulating the behavior of biological synapses and neurons.This is not only because MTJs can simulate biological behavior such as spike-timing dependence plasticity and leaky integrate-fire,but also because MTJs have intrinsic stochastic and oscillatory properties.These characteristics improve MTJs’bio-fidelity and reduce their power consumption.MTJs also possess advantages such as ultrafast dynamics and non-volatile properties,making them widely utilized in the field of neuromorphic computing in recent years.We conducted a comprehensive review of the development history and underlying principles of TMR,including a detailed introduction to the material and magnetic properties of MTJs and their temperature dependence.We also explored various writing methods of MTJs and their potential applications.Furthermore,we provided a thorough analysis of the characteristics and potential applications of different types of MTJs for neuromorphic computing.TMR-based devices have demonstrated promising potential for broad application in neuromorphic computing,particularly in the development of spiking neural networks.Their ability to perform on-chip learning with ultra-low power consumption makes them an exciting prospect for future a

关键词： spintronics TMR MTJ neuromorphic computing SNN