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Ultrafast photoemission electron microscopy:A multidimensional probe of nonequilibrium physics

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Chinese Physics B 2024年第3期33卷 24-57页

作者：戴亚南 Department of Physics Southern University of Science and Technology (SUSTech)Shenzhen 518055China Quantum science center of guangdong-hong kong-macao greater bay area (guangdong) Shenzhen 518045China

Exploring the realms of physics that extend beyond thermal equilibrium has emerged as a crucial branch of condensed matter physics *** aims to unravel the intricate processes involving the excitations,interactions,and annihilations of quasi-and many-body particles,and ultimately to achieve the manipulation and engineering of exotic non-equilibrium quantum phases on the ultrasmall and ultrafast spatiotemporal *** the inherent complexities arising from many-body dynamics,it therefore seeks a technique that has efficient and diverse detection degrees of freedom to study the underlying *** combining high-power femtosecond lasers with real-or momentum-space photoemission electron microscopy(PEEM),imaging excited state phenomena from multiple perspectives,including time,real space,energy,momentum,and spin,can be conveniently achieved,making it a unique technique in studying physics out of *** this context,we overview the working principle and technical advances of the PEEM apparatus and the related laser systems,and survey key excited-state phenomena probed through this surface-sensitive methodology,including the ultrafast dynamics of electrons,excitons,plasmons,spins,etc.,in materials ranging from bulk and nano-structured metals and semiconductors to low-dimensional quantum *** this review,one can further envision that time-resolved PEEM will open new avenues for investigating a variety of classical and quantum phenomena in a multidimensional parameter space,offering unprecedented and comprehensive insights into important questions in the field of condensed matter physics.

关键词： ultrafast photoemission electron microscopy ultrafast momentum microscopy excited state physics

Strong light–matter interactions based on excitons and the abnormal all-dielectric anapole mode with both large field enhancement and low loss

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Photonics Research 2024年第4期12卷 854-864页

作者： YAN-HUI DENG YU-WEI LU HOU-JIAO ZHANG Zhong-hong SHI ZHANG-KAI ZHOU XUE-HUA WANG State Key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-sen UniversityGuangzhou 510275China Quantum science center of guangdong–hong kong–macao greater bay area(guangdong) Shenzhen 518045China

The room temperature strong coupling between the photonic modes of micro/nanocavities and quantum emitters(QEs) can bring about promising advantages for fundamental and applied *** the electric fields(EFs) by using plasmonic modes and reducing their losses by applying dielectric nanocavities are widely employed approaches to achieve room temperature strong ***,ideal photonic modes with both large EFs and low loss have been ***,we propose the abnormal anapole mode (AAM),showing both a strong EF enhancement of~70-fold (comparable to plasmonic modes) and a low loss of 34 meV,which is much smaller than previous records of isolated all-dielectric *** realizing strong coupling,we further show that by replacing the normal anapole mode with the AAM,the lasing threshold of the AAM-coupled QEs can be reduced by one order of magnitude,implying a vital step toward on-chip integration of nanophotonic devices.

关键词： dielectric mode coupling

Optical scattering imaging with sub-nanometer precision based on position-ultra-sensitive giant Lamb shift

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science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 96-105页

作者： Zeyang Liao Yu-Wei Lu Wei Li Xue-Hua Wang State Key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-sen UniversityGuangzhou 510275China Quantum science center of guangdong-hong kong-macao greater bay area(guangdong) Shenzhen 518045China

The Lamb shift of a quantum emitter in close proximity to a plasmonic nanostructure can be three or more orders of magnitude larger than that in the free space and is ultra-sensitive to the emitter position and *** demonstrate that this large Lamb shift can be sensitively observed from the scattering or absorption spectrum dip shift of the coupled system when the plasmonic nanoparticle or tip scans the *** these observations,we propose a scanning optical scattering imaging method based on the plasmonic-enhanced Lamb shift with achieves sub-nanometer *** method is based on the scattering or absorption spectrum of the plasmon-emitter coupling system,which is free of the fluorescence quenching problem and easier to implement in a plasmon-emitter coupling *** addition,our scheme works even if the quantum emitter is slightly below the dielectric surface,which can bring about broader applications,such as detecting atoms and molecules or quantum dots above or under a surface.

关键词： Lamb shift plasmon optical scattering imaging

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Classification of spin Hall effect in two-dimensional systems

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Frontiers of physics 2024年第3期19卷 103-114页

作者： Longjun Xiang Fuming Xu Luyang Wang Jian Wang College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Quantum science center of guangdong-hongkong-macao greater bay area(guangdong) Shenzhen 518045China Department of Physics The University of Hong KongPokfulam RoadHong KongChina

Physical properties such as the conductivity are usually classified according to the symmetry of the underlying system using Neumann’s principle, which gives an upper bound for the number of independent components of the corresponding property tensor. However, for a given Hamiltonian, this global approach usually can not give a definite answer on whether a physical effect such as spin Hall effect (SHE) exists or not. It is found that the parity and types of spin-orbit interactions (SOIs) are good indicators that can further reduce the number of independent components of the spin Hall conductivity for a specific system. In terms of the parity as well as various Rashba-like and Dresselhaus-like SOIs, we propose a local approach to classify SHE in two-dimensional (2D) two-band models, where sufficient conditions for identifying the existence or absence of SHE in all 2D magnetic point groups are presented.

关键词： spin Hall effect symmetry two-dimensional system

Cryogenic transmission electron microscopy on beam-sensitive materials and quantum science

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Chinese Physics B 2024年第8期33卷 9-29页

作者：王刚林君浩 Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and TechnologyShenzhen 518055China Quantum science center of guangdong–hong kong–macao greater bay area(guangdong) Shenzhen 518045China

Transmission electron microscopy(TEM)offers unparalleled atomic-resolution imaging of complex materials and heterogeneous ***,high-energy imaging electrons can induce structural damage,posing a challenge for electron-beam-sensitive *** TEM(Cryo-TEM)has revolutionized structural biology,enabling the visualization of biomolecules in their near-native states at unprecedented *** low electron dose imaging and stable cryogenic environment in Cryo-TEM are now being harnessed for the investigation of electron-beam-sensitive materials and low-temperature quantum ***,we present a systematic review of the interaction mechanisms between imaging electrons and atomic structures,illustrating the electron beam-induced damage and the mitigating role of *** review then explores the advancements in low-dose Cryo-TEM imaging for elucidating the structures of organic-based ***,we showcase the application of Cryo-TEM in the study of strongly correlated quantum materials,including the detection of charge order and novel topological spin ***,we discuss the future prospects of Cryo-TEM,emphasizing its transformative potential in unraveling the complexities of materials and phenomena across diverse scientific disciplines.

关键词： cryogenic TEM low dose imaging quantum materials

Quantifying the Tension between Cosmological Models and JWST Red Candidate Massive Galaxies

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Research in Astronomy and Astrophysics 2024年第4期24卷 1-6页

作者： Jun-Chao Wang Zhi-Qi Huang Lu Huang Jianqi Liu School of Physics and Astronomy Sun Yat-sen UniversityZhuhai 519082China csst science center for the guangdong-hong kong-macao greater bay area Zhuhai519082China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China

We develop a Python tool to estimate the tail distribution of the number of dark matter halos beyond a mass threshold and in a given volume in a *** code is based on the extended Press-Schechter model and is computationally efficient,typically taking a few seconds on a personal laptop for a given set of cosmological *** high efficiency of the code allows a quick estimation of the tension between cosmological models and the red candidate massive galaxies released by the James Webb Space Telescope,as well as scanning the theory space with the Markov Chain Monte Carlo *** an example application,we use the tool to study the cosmological implication of the candidate galaxies presented in Labbéet *** standard Λcold dark matter(ΛCDM)model is well consistent with the data if the star formation efficiency can reach~0.3 at high *** a low star formation efficiency ε~0.1,theΛCDM model is disfavored at~2σ-3σconfidence level.

关键词： (cosmology:)cosmological parameters Galaxy:abundances Galaxy:formation

Single crystal growth and transport properties of narrow-bandgap semiconductor RhP_(2)

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Chinese Physics B 2024年第8期33卷 545-549页

作者：吴德胜郑萍雒建林 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China Quantum science center of guangdong–hong kong–macao greater bay area(guangdong) Shenzhen 518045China

We report the growth of high-quality single crystals of RhP_(2),and systematically study its structure and physical properties by transport,magnetism,and heat capacity ***-crystal x-ray diffraction reveals that RhP_(2) adopts a monoclinic structure with the cell parameters a=5.7347(10)A,b=5.7804(11)A,and c=5.8222(11)A,space group P2_(1)/c(No.14).The electrical resistivityρ(T)measurements indicate that RhP_(2) exhibits narrow-bandgap behavior with the activation energies of 223.1 meV and 27.4 meV for two distinct regions,*** temperaturedependent Hall effect measurements show electron domain transport behavior with a low charge carrier *** find that RhP_(2) has a high mobilityμ_(e)~210 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_(e)~3.3×10^(18)cm^(3) at 300 K with a narrow-bandgap *** high mobilityμ_(e) reaches the maximum of approximately 340 cm^(2)·V^(-1)·s^(-1)with carrier concentrations n_^(e)~2×10^(18)cm^(-3)at 100 *** magnetic phase transitions are observed from the susceptibilityχ(T)and specific heat C_(p)(T)measurements of RhP_(2).Our results not only provide effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.

关键词： single crystal growth narrow band system electrical transport high mobilities

Improving constraint onΩ_(m)from SDSS using marked correlation functions

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science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 207-224页

作者： Limin Lai Jiacheng Ding Xiaolin Luo Yizhao Yang Zihan Wang Keshi Liu Guanfu Liu Xin Wang Yi Zheng Zhaoyu Li Le Zhang Xiao-Dong Li School of Physics and Astronomy Sun Yat-sen University Zhuhai CampusZhuhai 519082China Department of Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Department of Astronomy Tsinghua UniversityBeijing 100084China csst science center for the guangdong-hong kong-macao greater bay area SYSUZhuhai 519082China Peng Cheng Laboratory Shenzhen 518000China

Large-scale structure(LSS)surveys will increasingly provide stringent constraints on our cosmological ***,the density-marked correlation function(MCF)has been introduced,offering an easily computable density-correlation *** have demonstrated that MCFs offer additional,independent constraints on cosmological models beyond the standard two-point correlation(2PCF).In this study,we apply MCFs for the first time to SDSS CMASS data,aiming to investigate the statistical information regarding clustering and anisotropy properties in the Universe and assess the performance of various weighting schemes in MCFs,and finally obtain constraints onΩ_(m).Upon analyzing the CMASS data,we observe that,by combining different weights(α=[-0.2,0,0.2,0.6]),the MCFs provide a tight and independent constraint on the cosmological parameterΩ_(m),yieldingΩ_(m)=0.293±0.006 at the 1σlevel,which represents a significant reduction in the statistical error by a factor of 3.4 compared to that from *** constraint is consistent with recent findings from the small-scale clustering of BOSS galaxies(Zhai et ***.J.948,99(2023))within the 1σ***,we also find that our estimate is lower than the Planck measurements by about 2.6σ,indicating the potential presence of new physics beyond the standard cosmological model if all the systematics are fully *** method outlined in this study can be extended to other surveys and datasets,allowing for the constraint of other cosmological ***,it serves as a valuable tool for forthcoming emulator analysis on the Chinese Space Station Telescope(csst).

关键词： large scale structure of universe dark energy cosmological parameters marked weighted correlation function

Bimodal growth of Fe islands on graphene

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Chinese Physics B 2024年第6期33卷 553-557页

作者：顾翊晟俞俏滟刘荡孙蓟策席瑞骏陈星森薛莎莎章毅杜宪宁旭辉杨浩管丹丹刘晓雪刘亮李耀义王世勇刘灿华郑浩贾金锋 Key Laboratory of Artificial Structures and Quantum Control TD Lee InstituteShenyang National Laboratory for Materials ScienceSchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Department of Physics Southern University of Science and TechnologyShenzhen 518055China Quantum science center of guangdong-hong kong-macao greater bay area(guangdong) Shenzhen 518045China

Magnetic metals deposited on graphene hold the key to applications in spintronics. Here, we present the results of Fe islands grown on graphene/Si C(0001) by molecular beam epitaxy, which are investigated by scanning tunneling microscopy. The two types of islands distinguished by flat or round tops are revealed, indicating bimodal growth of Fe. The atomic structures on the top surfaces of flat islands are also clearly resolved. Our results may improve the understanding of the mechanisms of metals deposited on graphene and pave the way for future spintronic applications of Fe/graphene systems.

关键词： graphene magnetism molecular beam epitaxy scanning tunneling microscopy