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High efficiency giant magnetoresistive device based on two-dimensional MXene(Mn_(2)NO_(2))

Frontiers of physics 2022年第5期17卷 17-26页

作者： Xiaolin Zhang Pengwei Gong Fangqi Liu Kailun Yao Jian Wu Sicong Zhu The State Key Laboratory for Refractories and Metallurgy Hubei Province Key Laboratory of Systems Science in Metallurgical ProcessCollaborative Innovation Center for Advanced SteelsInternational Research Institute for Steel TechnologyWuhan University of Science and TechnologyWuhan 430081China Wuhan National High Magnetic Field Center and School of Physics Huazhong University of Science and TechnologyWuhan 430074China College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China

Due to the unique electronic structure of half-metals,characterized by the conductivity of majority-spin and the band gap of minority-spin,these materials have emerged as suitable alternatives for the design of efficient giant magnetoresistive(GMR)*** on the first-principles calculations,an excellent GMR device has been designed by using two-dimensional(2D)half-metal Mn_(2)NO_(2).The results show that Mn_(2)NO_(2)has sandwiched between the Au/nMn_(2)NO_(2)(n=1,2,3)/Au heterojunction and maintains its half-metallic *** to the half-metallic characteristics of Mn_(2)NO_(2),the total current of the monolayer device can reach up to 1500 nA in the ferromagnetic *** low voltage,the maximum GMR is observed to be 1.15×1031%.Further,by increasing the number of layers,the ultra-high GMR at low voltage is still *** developed device is a spintronic device exhibiting the highest magnetoresistive ratio reported theoretically so ***,a significant negative differential resistance(NDR)effect is also observed in the *** to its excellent half-metallic properties and 2D structure,Mn_(2)NO_(2)is an ideal energy-saving GMR material.

关键词： half-metals Mn_(2)NO_(2) giant magnetoresistive

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High-Efficiency Photoelectric Detector Based on a p-n Homojunction of Monolayer Black Phosphorus

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Physical Review Applied 2023年第2期20卷 024027-024027页

作者： Xueying Zuo Jingjing Cheng Yulin Liang Fuming Xu Yanxia Xing Center for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen 518060 China

We numerically investigate the high-efficiency photovoltaic effect in a lateral p-n homojunction based on monolayer black phosphorus (MBP) by using the nonequilibrium Green’s function combined with the density-functional theory. Because of the built-in electric field of the p-n junction and the wrinkle structure of MBP, the photocurrent excited by either linearly or elliptically polarized light is significantly enhanced in a wide photon energy range. Moreover, because of the electron-photon interaction, the photocurrent is related to atomic orbitals through the polarizing angle of the polarized light. Therefore, we can read the orbital information of the band structure from the polarizing angular distribution of the photocurrent. These findings suggest the promising application of the MBP-based p-n homojunction in high-efficiency photoelectric devices and orbital-resolved photovoltaic detection.

关键词： optoelectronics Photocurrent Elemental semiconductors Junctions Monolayer films Photovoltaic absorbers Density functional calculations Green's function methods

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A Cross-Scale Multi-Branch Feature Fusion Based Method for Smoke and Fire Detection in Warehouses 24

A Cross-Scale Multi-Branch Feature Fusion Based Method for S...

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13th International Conference on Computing and Pattern Recognition, ICCPR 2024

作者： Bai, Yanbing Liu, Pengyu Liu, Weilong Deng, Yiyang Kong, Lili Chen, Shanji Chen, Jiali Yuan, Bowen School of Information Science and Technology Beijing Laboratory of Advanced Information Networks Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing University Of Technology Beijing China Information Technology Co. Ltd Dingzhou China Beijing-Dublin International College at BJUT Beijing University Of Technology Beijing China College of Physics and Electronic Information Engineering Qinghai Minzu University Qinghai China

ISBN: (纸本)9798400717482

To address the challenges of leakage, misdetection, and low accuracy caused by environmental complexity, object occlusion, and insufficient lighting in smoke and fire detection within warehouse scenarios, this paper proposes a cross-scale multi-branch feature fusion network for smoke and fire detection, named SF-YOLO. Firstly, a multi-branch feature enhancement module, Res2Net-C, is proposed to introduce an attention mechanism using a multi-branch feature fusion network, which not only extends the sensory field of the network, but also enhances the ability of extracting effective information, while effectively suppressing the interference of irrelevant information. It effectively improves detection performance under complex environmental conditions and in the presence of object occlusion. Secondly, a cross-scale feature fusion network structure, MSFPN, is proposed, which achieves effective complementation and fusion of high-level and low-level information by establishing hopping connections between features at different scales, and significantly improves the recognition accuracy of the type and location of the smoke and fire in low-light conditions. In addition, the added small target detection layer further improves the network's ability to detect small targets. Finally, in order to better adapt to pyrotechnic targets with variable morphology, EIoU is adopted as the bounding box loss function. Test results on a self-built dataset show that SF-YOLO achieves a mean accuracy rate (mAP) of 87.5% in the task of detecting smoke and fire under multiple environmental factors in a warehouse scenario, proving its effectiveness and usefulness. © 2024 Copyright held by the owner/author(s).

关键词： Deep learning

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Observation of acoustic Floquet π modes in a time-varying lattice

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Physical Review B 2024年第2期109卷 L020302-L020302页

作者： Zhao-xian Chen An Chen Yu-Gui Peng Zheng-wei Li Bin Liang Jing Yang Xue-Feng Zhu Yan-qing Lu Jian-chun Cheng Collaborative Innovation Center of Advanced Microstructures and Key Laboratory of Modern Acoustics MOE Institute of Acoustics Department of Physics Nanjing University Nanjing 210093 People's Republic of China College of Engineering and Applied Sciences Nanjing University Nanjing 210093 People's Republic of China School of Physics and Innovation Institute Huazhong University of Science and Technology Wuhan Hubei 430074 People's Republic of China

Time modulation provides an important degree of freedom for classical wave steering in topological manners. Rather than using the spatial dimension to mimic time, here we design and implement an acoustic temporal lattice with time-varying couplings to demonstrate a unique type of strongly localized Floquet π modes that are gauge independent and can be robustly excited at the frequency in the nontrivial band gap. We observe the topological phase transitions by changing modulation frequency, consistent with the calculated quasienergy spectra. Our work paves the way for investigating intrinsic characteristics of various temporal systems and may inspire other intriguing discoveries in topological systems, such as higher-order temporal Floquet topological insulators.

关键词： Linear acoustics Phononic crystals Floquet systems

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Ion-exchange-induced Bi and K dual-doping of TiOx in molten salts for high-performance electrochemical nitrogen reduction

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Journal of Energy Chemistry 2022年第6期31卷 26-34,I0002页

作者： Hao Li Liqun Wang Nan Li Jianmin Feng Feng Hou Sihui Wang Ji Liang Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjin 300350China Applied Physics Department College of Physics and Materials ScienceTianjin Normal UniversityTianjin 300387China School of Aeronautics and Astronautics Tianjin Sino-German University of Applied SciencesTianjin 300350China

Electrocatalytic nitrogen reduction reaction (e NRR) at the ambient conditions is attractive for ammonia(NH_(3)) synthesis due to its energy-efficient and eco-friendly features. However, the extremely strong N≡N triple-bonds in nitrogen molecules and the competitive hydrogen evolution reaction lead to the unsatisfactory NH_(3) yield and the Faradaic efficiency (FE) of e NRR, making the development of high-performance catalysts with adequate active sites and high selectivity essential for further development of e *** this, we herein report a Bi and K dual-doped titanium oxide (BTO@KTO) material, which is prepared by a cation exchange reaction between K_(2)Ti_(4)O_(5) and molten BiCl_(2), for high-performance e NRR catalysts. Benefiting from the controllable molten-salt cation exchange process, a highly active surface containing Bi/K sites and rich oxygen vacancies has been obtained on titanium oxide. Under the synergy of these two merits, an efficient e NRR catalysis, with the NH_(3) yield rate of 32.02 μg h^(-1)mg_(cat)^(-1) and the FE of 12.71%, has been achieved, much superior to that of pristine K_(2)Ti_(4)O_(9). This work thus offers a highperformance electrocatalyst for e NRR, and more importantly, a versatile cation-exchange strategy for efficiently manipulating materials’ functionalities.

关键词： Molten salt Electrocatalysis Nitrogen fixation Cation exchange Dual doping

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Surface-dependent Majorana vortex phases in topological crystalline insulators

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Physical Review B 2025年第14期111卷 144501-144501页

作者： Xun-Jiang Luo Xiao-Hong Pan Yilin Shi Fengcheng Wu School of Physics and Technology Wuhan University Wuhan 430072 China Department of Physics Hong Kong University of Science and Technology Clear Water Bay 999077 Hong Kong China Department of Physics College of Physics Optoelectronic Engineering Jinan University Guangzhou 510632 China Wuhan Institute of Quantum Technology Wuhan 430206 China

The topological crystalline insulator SnTe exhibits surface-dependent Dirac cones, which are located at non-time-reversal-invariant momenta on the (001) and (110) surfaces, but at time-reversal-invariant momenta on the (111) surface. Motivated by the recent experimental evidence of Majorana vortex end modes (MVEMs) and their hybridization on the (001) surface [Liu et al., Nature (London) 633, 71 (2024)], we present a comprehensive investigation of Majorana vortex phases in SnTe with proximity-induced superconductivity, including topological classification, surface-state Hamiltonians analysis, and lattice model calculations. By utilizing rotational and magnetic mirror symmetries, we present two equivalent methods to reveal the topology of Majorana phases on different surfaces. We find that the MVEMs on the (001) and (110) surfaces are protected by both magnetic group and rotational symmetries. In contrast, the MVEMs on the (111) surface are protected by magnetic group or particle-hole symmetry. Due to the different properties of Dirac fermions in the Γ¯ and M¯ valleys on the (111) surfaces, including Fermi velocities and energy levels, we find that abundant vortex phase transitions can occur for the [111]-direction vortex. As the chemical potential shifts from the surface to bulk states, the number of robust MVEMs can change from 2→1→0. These vortex transitions are characterized by both Z winding number and Z2 pfaffian topological invariants.

关键词： Hamiltonians

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Free-phase-matching and tunable-gain phase-sensitive amplification based on thin-film lithium niobate

Free-phase-matching and tunable-gain phase-sensitive amplifi...

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CLEO: science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Wang, Yanqun Liu, Xiaoyue Zhu, Chunfan Liu, Lin Huang, Fujing Zhu, Yuntao Chen, Mengwen Xie, Zhenda Zhu, Shining Yu, Siyuan Lin, Zhongjin Cai, Xin lun State Key Laboratory of Optoelectronic Materials and Technologies School of Electronics and Information Technology Sun Yat-sen University Guangzhou510275 China National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences College of Electronic Science and Engineering School of Physics Nanjing University Nanjing210093 China

Based on substrate-removed thin-film lithium niobate, we demonstrate a tunable phase-sensitive amplification, which can achieve an extinction ratio of 30.6 dB and a maximum gain of 23 dB in wavelength ranges of 1530-1...

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Free-phase-matching and tunable-gain phase-sensitive amplification based on thin-film lithium niobate

Free-phase-matching and tunable-gain phase-sensitive amplifi...

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2024 Conference on Lasers and Electro-Optics, CLEO 2024

ISBN: (纸本)9781957171395

关键词： Optical waveguides

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Hybrid-order Poincaré sphere beam fiber laser

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Optics Express 2025年第12期33卷 26272-26285页

作者： Han Wang Zhiyuan Ma Jiantai Dou Li Fan Bo Li Youyou Hu School of Science Jiangsu University of Science and Technology Zhenjiang 212100 China School of Optoelectronic Science and Engineering University of Electronic Science and Technology of China Chengdu 611731 China College of Physics Science and Technology Institute of Applied Photonic Technology Yangzhou University Yangzhou 225002 China School of Optical and Electronic Information Huazhong University of Science and Technology Wuhan 430074 China Optics Valley Laboratory Hubei 430074 China

In this work, a hybrid-order Poincaré sphere (HyOPS) beam fiber laser was reported and demonstrated, which can yield the vector vortex beam in the cavity directly and realize the polarization evolution at an arbitrary position on the HyOPS. The conversion between the Pancharatnam topological charge and polarization topological charge was realized by the Pancharatnam-Berry phase modulation in the spatial loop of a fiber laser. Then, the HyOPS beam laser was established, achieving continuous wave and mode-locked operations. The mode-locked HyOPS beam laser can be achieved with pulse width, repetition frequency, center wavelength, and 3 dB bandwidth of 128 ps, 13.74 MHz, 1039.84 nm, and 2.3 nm at [-4, 2, Φ, Θ], respectively. [m, n, Φ, Θ] is the mode vector, where m and n represent the topological charges of the vortex beams at the two poles of HyOPS; Φ and Θ represent the coordinates of HyOPS, respectively. This intra-cavity approach offers a compact and integrated solution to generate full-state HyOPS beams, and provides a new strategy for source-level design of complex structured light. The results may be instructive for the generation of the HyOPS beam directly.

关键词： Azimuthally polarized beams Cylindrical vector beams Fiber lasers Free space optics Laser beams Spatial light modulators

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Kerr-lens Mode-locked GHz-repetition-rate Yb:CALYO Laser with 11-W Average Power

Kerr-lens Mode-locked GHz-repetition-rate Yb:CALYO Laser wit...

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2024 Laser Applications Conference, LAC 2024

作者： Tao, Jie Tian, Wenlong Zheng, Li Wang, Geyang Yu, Yang Xu, Xiaodong Wei, Zhiyi Zhu, Jiangfeng School of Optoelectronic Engineering Xidian University Xi’an710071 China School of Physics and Telecommunication Engineering Shaanxi University of Technology Hanzhong723001 China Academy of Advanced Interdisciplinary Research Xidian University Xi’an710071 China School of Physics and Electronic Engineering Jiangsu Normal University Xuzhou221116 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Science Beijing100190 China

关键词： Laser mode locking

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