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Strain Tunable Berry Curvature Dipole, Orbital Magnetization and Nonlinear Hall Effect in WSe_(2) Monolayer

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Chinese Physics Letters 2021年第1期38卷 99-104页

作者：秦茂森朱鹏飞叶兴国徐文正宋振豪梁晶刘开辉廖志敏 State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking UniversityBeijing 100871China

The electronic topology is generally related to the Berry curvature,which can induce the anomalous Hall effect in time-reversal symmetry breaking systems.Intrinsic monolayer transition metal dichalcogenides possesses two nonequivalent K and K’ valleys,having Berry curvatures with opposite signs,and thus vanishing anomalous Hall effect in this system.Here we report the experimental realization of asymmetrical distribution of Berry curvature in a single valley in monolayer WSe_(2) via applying uniaxial strain to break C_(3v) symmetry.As a result,although the Berry curvature itself is still opposite in K and K’ valleys,the two valleys would contribute equally to nonzero Berry curvature dipole.Upon applying electric field E,the emergent Berry curvature dipole D would lead to an out-of-plane orbital magnetization M ∝ D·E,which further induces an anomalous Hall effect with a linear response to E^(2),known as nonlinear Hall effect.We show the strain modulated transport properties of nonlinear Hall effect in monolayer WSe_(2) with moderate hole-doping by gating.The second-harmonic Hall signals show quadratic dependence on electric field,and the corresponding orbital magnetization per current density M/J can reach as large as 60.In contrast to the conventional Rashba-Edelstein effect with in-plane spin polarization,such current-induced orbital magnetization is along the out-of-plane direction,thus promising for high-efficient electrical switching of perpendicular magnetization.

关键词： Berry curvature magnetization

Innovation in metamaterials and beyond:an interview with Prof.Xiang Zhang

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Advanced Photonics 2022年第2期4卷 3-6页

作者： Ren-Min Ma Peking University School of PhysicsState Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronicsBeijingChina Collaborative Innovation center of Quantum Matter BeijingChina

Ren-Min Ma: Prof. Zhang, you have made a series of groundbreaking discoveries in metamaterials. How did you get started in this field?Xiang Zhang: The research in metamaterials started about two decades ago. We are ve... 详细信息

关键词： interview breaking Xiang

低对称性的亚波长阵列增强型的GeSe偏振探测器（英文）

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science Bulletin 2023年第2期68卷 173-179页

作者：周子琦沈涛王盼郭泉林王卿赫马辰俊辛凯耀赵凯于雅俐秦彪刘岳阳杨珏晗洪浩刘开辉刘灿邓惠雄魏钟鸣 State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences State Key Laboratory for Mesoscopic Physics Frontiers Science Centre for Nano-optoelectronics School of Physics Peking University center of Materials science and optoelectronics Engineering University of Chinese Academy of Sciences Department of Physics Renmin University of China

偏振敏感光电探测器可通过探测光偏振态的变化从而分辨纹理、应力和粗糙度等多种信息,在安全、医疗诊断和航空航天领域具有独特的优势.基于面内各向异性的二维材料的偏振光探测器可简化传统探测器的复杂透镜系统,促进了光电器件的集成... 详细信息

偏振敏感光电探测器可通过探测光偏振态的变化从而分辨纹理、应力和粗糙度等多种信息,在安全、医疗诊断和航空航天领域具有独特的优势.基于面内各向异性的二维材料的偏振光探测器可简化传统探测器的复杂透镜系统,促进了光电器件的集成化与小型化.然而,基于面内各向异性的二维材料的偏振光探测器的光电流各向异性比不足(通常小于10),限制了偏振信号的检测分辨率.本文设计了基于二维硒化亚锗(GeSe)的亚波长阵列(SWA)结构,进一步提高其各向异性灵敏度,并将光电流各向异性从1.6提高到18.本研究发现,SWA结构可以进一步增强电荷分布的不对称性,提高GeSe材料在扶手椅方向上的光吸收和光电跃迁概率,从而提高了偏振灵敏度.此外,基于GeSe SWA的光电探测器在808 nm的近红外波长下表现出宽的功率范围(40 dB)和弱光探测能力(0.1 LUX).该工作为提高二维材料的偏振灵敏度提供了可行性指导,将有利于促进高分辨率偏振成像传感器的发展.

关键词： Germanium selenium (GeSe) Polarization-sensitive photodetectors Sub-wavelength array Anisotropy ratio

High-dimensional quantum information processing on programmable integrated photonic chips

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science China(Information sciences) 2023年第8期66卷 5-22页

作者： Yulin CHI Yue YU Qihuang GONG Jianwei WANG State Key Laboratory for Mesoscopic Physics School of Physics Peking University Frontiers Science Center for Nano-optoelectronics and Collaborative Innovation center of Quantum Matter Peking University Peking University Yangtze Delta Institute of optoelectronics Collaborative Innovation center of Extreme Optics Shanxi University Hefei National Laboratory

This study reviews the recent progress of high-dimensional quantum information processing with photons. We first introduce the basic language of high-dimensional quantum information, including the representation of quantum dits(qudits), unitary operations of qudit states, and the general format of quantum algorithms with qudits. We discuss experimental implementations of high-dimensional quantum information processing and quantum computing in photonic systems, particularly in integrated quantum photonic platforms. We also discuss how qudit-based quantum photonic devices and systems can be adopted for further improving qubit-based quantum computation and quantum simulation.

关键词： high-dimensional quantum information processing quantum computation integrated quantum photonics

Monolithic thin film lithium niobate electro-optic modulator with over 110 GHz bandwidth

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Chinese Optics Letters 2022年第2期20卷 148-152页

作者：杨帆方先松陈心羽朱立新张帆陈章渊李艳萍 State Key Laboratory of Advanced Optical Communication Systems and Networks Department of ElectronicsPeking UniversityBeijing 100871China Frontiers Science Center for Nano-optoelectronics Peking UniversityBeijing 100871China

High-performance thin film lithium niobate(LN) electro-optic modulators with low cost are in demand. Based on photolithography and wet etching, we experimentally demonstrate a thin film LN Mach–Zehnder modulator with a 3 d B bandwidth exceeding 110 GHz, which shows the potential of boosting the throughput and reducing cost. The fabricated modulator also exhibits a comparable low half-wave voltage-length product of ~2.37 V · cm, a high extinction ratio of >23 d B, and the propagation loss of optical waveguides of ~0.2 d B/cm. Besides, six-level pulse amplitude modulation up to 250 Gb/s is successfully achieved.

关键词： lithium niobate electro-optic modulator high bandwidth photolithography wet etching

Chiral emission and Purcell enhancement in a hybrid plasmonic-photonic microresonator

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Light(science & Applications) 2020年第1期9卷 1961-1962页

作者： Qi-Tao Cao You-Ling Chen Yun-Feng Xiao Frontiers Science Center for Nano-optoelectronics&School of Physics Peking UniversityBeijing 100871China State Key Laboratory on Integrated optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

A high-Q hybrid plasmonic-photonic microresonator,which consists of a dielectric microdisk hybridized with a plasmonic nanoantenna dimer,enables an enlarged local density of states of the optical field and chiral prop... 详细信息

关键词： cavity plasmon Chiral

Strain-dependent resistance and giant gauge factor in monolayer WSe2

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Chinese Physics B 2021年第9期 413-417页

作者：秦茂森叶兴国朱鹏飞徐文正梁晶刘开辉廖志敏 State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of Physics Peking University

We report the strong dependence of resistance on uniaxial strain in monolayer WSeat various temperatures, where the gauge factor can reach as large as 2400. The observation of strain-dependent resistance and giant gauge factor is attributed to the emergence of nonzero Berry curvature dipole. Upon increasing strain, Berry curvature dipole can generate net orbital magnetization, which would introduce additional magnetic scattering, decreasing the mobility and thus conductivity. Our work demonstrates the strain engineering of Berry curvature and thus the transport properties, making monolayer WSepotential for application in the highly sensitive strain sensors and high-performance flexible electronics.

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Orbit-Transfer Torque Driven Field-Free Switching of Perpendicular Magnetization

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Chinese Physics Letters 2022年第3期39卷 89-93页

作者：叶兴国朱鹏飞徐文正尚念泽刘开辉廖志敏 State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking UniversityBeijing 100871China

The reversal of perpendicular magnetization(PM)by electric control is crucial for high-density integration of low-power magnetic random-access memory.Although the spin-transfer torque and spin-orbit torque technologies have been used to switch the magnetization of a free layer with perpendicular magnetic anisotropy,the former has limited endurance because of the high current density directly through the junction,while the latter requires an external magnetic field or unconventional configuration to break the symmetry.Here we propose and realize the orbit-transfer torque(OTT),that is,exerting torque on the magnetization using the orbital magnetic moments,and thus demonstrate a new strategy for current-driven PM reversal without external magnetic field.The perpendicular polarization of orbital magnetic moments is generated by a direct current in a few-layer WTe_(2)due to the existence of nonzero Berry curvature dipole,and the polarization direction can be switched by changing the current polarity.Guided by this principle,we construct the WTe_(2)/Fe_(3)GeTe_(2)heterostructures to achieve the OTT driven field-free deterministic switching of PM.

关键词： polarization switched Switching

A strategic review on processing routes towards scalable fabrication of perovskite solar cells

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Journal of Energy Chemistry 2022年第1期31卷 538-560,I0014页

作者： Yingzhuang Ma Qing Zhao Wenzheng College of Soochow University Suzhou 215104JiangsuChina State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking UniversityBeijing 100871China Peking University Yangtze Delta Institute of optoelectronics Nantong 226010JiangsuChina

Perovskite solar cells have reached a power-conversion efficiency(PCE) of 25.6%,showing great potential with reliable moisture and heat stability.Most results are achieved on small-area devices,using conventional thin-film processing technologies like spin-coating method.However,such approaches may not be upscaled for large-area substrates.Thus,strategies and materials need to be developed for manufacturing processing routes to realize future commercial photovoltaic fabrications.Notable results have been achieved on large-area perovskite solar cells.In this review,similarities and differences of large-area perovskite fabrication mechanisms between the various pathways are investigated,especially on the parameters affecting the nucleation and crystal growth kinetics.Moreover,the methods for large-area transporting layers and electrodes are discussed,and some key issues from cells to modules.Challenges and opportunities are proposed to pave the way of high-efficiency perovskite solar modules.

关键词： Perovskite Solar cell Large-area Commercialization Scalable fabrication