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Robust enhancement of valley polarization and quantum yield in composition grading lateral heterostructure of MoS2-WS2 monolayer

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Progress in Natural Science:Materials International 2024年第1期34卷 187-193页

作者： Mengke Kang Cheng Zhang Congpu Mu Kun Zhai Tianyu Xue Bochong Wang Fusheng Wen Yingchun Cheng Jianyong Xiang Jun-Feng Dai Anmin Nie Zhongyuan Liu Center for High Pressure Science State Key Laboratory of Metastable Materials Science and Technology Yanshan University Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen key laboratory of Quantum Science and Engineering

Valley degeneracy can be broken owing to the strong spin-orbit coupling in two-dimensional transition metal dichalcogenides（2D-TMDCs）. Valley-dependent interaction of carriers in TMDCs with different circular polarizations of light offers valley degree-of-freedom besides charge and spin to carry information. Thus, bandgap engineering of 2D-TMDCs plays a critical role in developing practical valleytronic devices. Hereby, we demonstrate a great enhancement in quantum yield as well as polarization of monolayer MoS2achieved by gradually alloying W atoms in MoS2. By appropriately setting a time offset between the evaporation of MoO3and WO3precursors during chemical vapor deposition, a compositionally graded heterostructure of MoS2-WS2monolayer can be readily grown at large scale. Raman and transmission electron microscopy measurements demonstrate that the interface possesses a steep gradient in composition, spanning from MoS2to WS2over a length ～2 μ*** to pure monolayer MoS2, the photoluminescence intensity at the compositionally graded interface of Mo1-xWxS2was observed to increase by a factor of 16 owing to the effective separation of photogenerated carriers by the built-in electric field. Particularly, a remarkably high polarization of 70% at 16 K is demonstrated for the compositionally graded interface of Mo1-xWxS2, which is ～1.4 times larger than that in MoS2and is attributed to the combined effect of the alloyed structure and graded bandgap. Such an engineering scheme with a graded bandgap offers new approach for the development of high-efficiency valleytronics devices.

关键词： Transition metal dichalcognide monolayer Compositionally graded in-plane heterostructure Chemical vapor deposition Valley polarization Quantum yield

Ferromagnetism and insulating behavior with a logarithmic temperature dependence of resistivity in Pb_(10-x)Cux(PO_(4))_(6)O

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Science China(physics,Mechanics & Astronomy) 2024年第1期67卷 106-111页

作者： Yuhang Zhang Cong Liu Xiyu Zhu Hai-Hu Wen Center for Superconducting physics and Materials National Laboratory of Solid State Microstructures and Department of PhysicsNational Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Recent claim of discovering above-room-temperature superconductivity(Tc≈400 K)at ambient pressure in copper doped apatite Pb10(PO_(4))_(6)O has stimulated world-wide enthusiasm and impulse of motion.A lot of follow-up works have been carried out with controversial *** check whether superconductivity is really present or absent in the material,we need samples which should have a rather pure phase of Pb_(10-x)Cux(PO_(4))_(6)*** we report the characterization results from the Pb_(10-x)Cux(PO_(4))_(6)O with a fraction of about 97 wt.%inferred from the fitting to the X-ray diffraction pattern,if assuming Cu2S as the only *** resistivity measurements show that it is a semiconductor characterized roughly by a ln(1/T)temperature dependence in wide temperature region without trace of *** measurements show that it has a general ferromagnetic signal with a weak superparamagnetic *** grains of the sample show clear interactions with a Nb Fe B *** detected Cu concentration is much lower than the expected nominal *** results show the absence of metallicity and superconductivity in Pb_(10-x)Cux(PO_(4))_(6)O at ambient pressure,and suggest the presence of strong correlation effect.

关键词： superconductivity Pb10(PO4)6O ferromagnetic correlation effect

Broadband and fabrication-tolerant 3-dB couplers with topological valley edge modes

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Light(Science & Applications) 2024年第8期13卷 1623-1630页

作者： Guo-Jing Tang Xiao-Dong Chen Lu Sun Chao-Heng Guo Meng-Yu Li Zhong-Tao Tian Hou-Hong Chen Hong-Wei Wang Qi-Yao Sun Ying-Di Pan Xin-Tao He Yi-Kai Su Jian-Wen Dong School of physics&state key laboratory of Optoelectronic Materials and Technologies Sun Yat-sen UniversityGuangzhou 510275China state key laboratory of Advanced Optical Communication Systems and Networks Department of Electronic EngineeringShanghai Jiao Tong UniversityShanghai 200240China

3-dB couplers,which are commonly used in photonic integrated circuits for on-chip information processing,precision measurement,and quantum computing,face challenges in achieving robust performance due to their limited 3-dB bandwidths and sensitivity to fabrication *** address this,we introduce topological physics to nanophotonics,developing a framework for topological 3-dB *** couplers exhibit broad working wavelength range and robustness against fabrication dimensional *** leveraging valley-Hall topology and mirror symmetry,the photonic-crystal-slab couplers achieve ideal 3-dB splitting characterized by a wavelength-insensitive scattering *** analysis confirms the superiority on broad bandwidth of 48 nm and robust splitting against dimensional errors of 20 *** further propose a topological interferometer for on-chip distance measurement,which also exhibits robustness against dimensional *** extension of topological principles to the fields of interferometers,may open up new possibilities for constructing robust wavelength division multiplexing,temperature-drift-insensitive sensing,and optical coherence tomography applications.

关键词： topological splitting insensitive

Conceptual transition from molecular to atomic: unleashing a new era in hydrogen therapy for chronic disease

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National Science Review 2024年第4期11卷 17-18页

作者： Zhigang Zou Eco-materials and Renewable Energy Research Center (ERERC) Jiangsu Key Laboratory for Nano Technology National Laboratory of Solid State Microstructures and Department of PhysicsNanjing University

The dysregulated overexpression of reactive oxygen and nitrogen species (RONS)intricately links to the occurrence and development of diverse chronic diseases[1–3]. Hydrogen therapy stands out as a promising treatment methodology recognized for effectively mitigating RONS and maintaining intracellular redox equilibrium, thereby yielding therapeutic benefits [4,5].

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From Topological Nodal-Line Semimetals to Quantum Spin Hall Insulators in Tetragonal SnX Monolayers(X=F,Cl,Br,I)

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Chinese physics Letters 2024年第6期41卷 98-111页

作者：朱晔赵宝薛阳徐玮徐文婷杨中芹 state key laboratory of Surface physics Key Laboratory of Computational Physical Sciences(MOE)and Department of PhysicsFudan UniversityShanghai 200433China Shandong key laboratory of Optical Communication Science and Technology School of Physics Science and Information TechnologyLiaocheng UniversityLiaocheng 252059China School of physics East China University of Science and TechnologyShanghai 200237China Shanghai Qi Zhi Institute Shanghai 200030China

Two-dimensional(2D)topological materials have recently garnered significant interest due to their profound physical properties and promising applications for future quantum *** various topological states within one type of materials is,however,seldom *** on first-principles calculations and tightbinding models,we investigate topological electronic states in a novel family of 2D halogenated tetragonal stanene(T-SnX,X=F,Cl,Br,I).All the four monolayers are found to be unusual topological nodal-line semimetals(NLSs),protected by a glide mirror *** spin-orbit coupling(SOC)is turned on,T-SnF and TSnCl are still ascertained as topological NLSs due to the remaining band inversion,primarily composed of Sn pxy orbitals,while T-Sn Br and T-SnI become quantum spin Hall *** phase transition is ascribed to moving up in energy of Sn s orbitals and increasing of SOC *** topology origin in the materials is uniformly rationalized through elementary band *** robust and diverse topological states found in the 2D T-SnX monolayers position them as an excellent material platform for development of innovative topological electronics.

关键词： topological metals quantum

Electronic Correlation and Pseudogap-Like Behavior of High-Temperature Superconductor La_(3)Ni_(2)O_(7)

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Chinese physics Letters 2024年第8期41卷 82-93页

作者： Yidian Li Xian Du Yantao Cao Cuiying Pei Mingxin Zhang Wenxuan Zhao Kaiyi Zhai Runzhe Xu Zhongkai Liu Zhiwei Li Jinkui Zhao Gang Li Yanpeng Qi Hanjie Guo Yulin Chen Lexian Yang state key laboratory of Low Dimensional Quantum physics Department of PhysicsTsinghua UniversityBeijing 100084China key Lab for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou UniversityLanzhou 730000China Songshan Lake Materials laboratory Dongguan 523808China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China ShanghaiTech laboratory for Topological physics Shanghai 200031China Shanghai key laboratory of High-Resolution Electron Microscopy ShanghaiTech UniversityShanghai 201210China department of physics Clarendon LaboratoryUniversity of OxfordParks RoadOxford OX13PUUK Frontier Science Center for Quantum Information Beijing 100084China

High-temperature superconductivity(HTSC)remains one of the most challenging and fascinating mysteries in condensed matter ***,superconductivity with transition temperature exceeding liquid-nitrogen temperature is discovered in La_(3)Ni_(2)O_(7) at high pressure,which provides a new platform to explore the unconventional *** this work,using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation,we systematically investigate the electronic structures of La_(3)Ni_(2)O_(7) at ambient *** experiments are in nice agreement with ab initio calculations after considering an orbital-dependent band renormalization *** strong electron correlation effect pushes a flat band of d_(z^(2))𝑧2 orbital component below the Fermi level(E_(F)),which is predicted to locate right at E_(F) under high ***,the d_(x^(2)−y^(2)) band shows pseudogap-like behavior with suppressed spectral weight and diminished quasiparticle peak near E_(F).Our findings provide important insights into the electronic structure of La_(3)Ni_(2)O_(7),which will shed light on understanding of the unconventional superconductivity in nickelates.

关键词： effect. superconductivity orbital

Characteristics of cell motility during cell collision

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Chinese physics B 2024年第2期33卷 72-77页

作者：马一凯李娜陈唯 state key laboratory of Surface physics and department of physics Fudan UniversityShanghai 200438China China National Center for Bioinformation Beijing 100101China National Genomics Data Center Beijing Institute of GenomicsChinese Academy of SciencesBeijing 100101China

Quantitative examination of cellular motion and intercellullar interactions possesses substantial relevance for both biology and ***,the effects of intercellular interactions during cellular locomotion remain under-explored in experimental *** such,this study seeks to bridge this research gap,adopting Dictyostelium discoideum(Dicty)cells as a paradigm to investigate variations in cellular motion during reciprocal *** aim to attain a comprehensive understanding of how cell interactions influence cell *** observing and processing the motion trajectories of colliding cells under diverse chemical environments,we calculated the diffusion coefficient(D)and the persistence time(τ),using mean square *** analysis of the relationship dynamics between D andτprior to the collisions reveals intricate and non-monotonic alterations in cell movements during *** quantitatively scrutinizing theτtrend,we were able to categorize the cellular responses to interactions under different ***,we ascertained that the effect of cell interactions during collisions in Dicty cells emulates a classical sigmoid *** discovery suggests that cellular responses might comply with a pattern akin to the Weber–Fechner law.

关键词： cell migration random walk cell-cell interaction

Coexistence of Dirac and Weyl points in non-centrosymmetric semimetal NbIrTe_(4)

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Chinese physics B 2024年第4期33卷 146-151页

作者：刘清馨付阳丁鹏飞马欢郭朋杰雷和畅王善才 department of physics Key Laboratory of Quantum State Construction and ManipulationRenmin University of ChinaBeijing 100872China Beijing key laboratory of Opto-Electronic Functional Materials&Micro-Nano Devices Renmin University of ChinaBeijing 100872China

Using angle-resolved photoemission spectroscopy and density functional theory calculations methods,we investigate the electronic structures and topological properties of ternary tellurides NbIrTe_(4),a candidate for type-II Weyl *** demonstrate the presence of several Fermi arcs connecting their corresponding Weyl points on both termination surfaces of the topological *** analysis reveals the existence of Dirac points,in addition to Weyl points,giving both theoretical and experimental evidences of the coexistence of Dirac and Weyl points in a single *** findings not only confirm NbIrTe_(4) as a unique topological semimetal but also open avenues for exploring novel electronic devices based on its coexisting Dirac and Weyl fermions.

关键词： Fermi arc Weyl point Dirac point angle-resolved photoemission spectroscopy

Spatial search weighting information contained in cell velocity distribution

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Chinese physics B 2024年第2期33卷 522-528页

Cell migration plays a significant role in physiological and pathological *** the characteristics of cell movement is crucial for comprehending biological processes such as cell functionality,cell migration,and cell–cell *** of the fundamental characteristics of cell movement is the specific distribution of cell speed,containing valuable information that still requires comprehensive *** article investigates the distribution of mean velocities along cell trajectories,with a focus on optimizing the efficiency of cell food search in the context of the entire *** confirm that the specific velocity distribution in the experiments corresponds to an optimal search efficiency when spatial weighting is *** simulation results indicate that the distribution of average velocity does not align with the optimal search efficiency when employing average spatial ***,when considering the distribution of central spatial weighting,the specific velocity distribution in the experiment is shown to correspond to the optimal search *** simulations reveal that for any given distribution of average velocity,a specific central spatial weighting can be identified among the possible central spatial weighting that aligns with the optimal search ***,our work presents a method for determining the spatial weights embedded in the velocity distribution of cell *** results have provided new avenues for further investigation of significant topics,such as relationship between cell behavior and environmental conditions throughout their evolutionary history,and how cells achieve collective cooperation through cell-cell communication.

关键词： cell migration foraging efficiency random walk spatial search weight