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Electronic structures and Mott state of epitaxial TaS_(2) monolayers

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 91-97页

作者： Qichao Tian Chi Ding Xiaodong Qiu Qinghao Meng Kaili Wang Fan Yu Yuyang Mu Can Wang Jian Sun Yi Zhang national laboratory of solid state microstructure School of PhysicsNanjing UniversityNanjing 20093China Collaborative Innovation Center of Advanced microstructures Nanjing UniversityNanjing 210093China School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Hefei national laboratory Hefei 230088China

Layered material TaS2hosts multiple structural phases and exotic correlated quantum states,including charge density wave(CDW),superconductivity,quantum spin liquid,and Mott insulating ***,we synthesized TaS_(2)monolayers in H and T phases using the molecular beam epitaxial(MBE)method and studied their electronic structures via angle-resolved photoemission spectroscopy(ARPES).We found that the H phase TaS_(2)(H-TaS_(2))monolayer is metallic,with an energy band crossing the Fermi *** contrast,the T phase TaS_(2)(T-TaS_(2))monolayer shows an insulated energy gap at the Fermi level,while the normal calculated band structure implies it should be metallic without any band ***,by considering Hubbard interaction potential U,further density functional theory(DFT)calculation suggests that monolayer T-TaS_(2)could be a CDW Mott insulator,and the DFT+U calculation matches well with the ARPES *** significantly,the temperature-dependent ARPES result indicates that the CDW Mott state in the T-TaS_(2)monolayer is more robust than its bulk counterpart and can persist at room *** results reveal that the dimensional effect can enhance the CDW Mott state and provide valuable insights for further exploring the exotic properties of monolayer TaS2.

关键词： temperature monolayer state

Cl- ions accelerating interface charge transfer in a Si/In2S3 Faradaic junction photocathode for solar seawater splitting

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Science China Chemistry 2024年第9期67卷 2923-2929页

作者： Jun Luo Ruotong Bao Hongzheng Dong Ye Fu Dongjian Jiang Bo Wang Yuzhan Zheng Qiong Wang Wenjun Luo Zhigang Zou Eco-materials and Renewable Energy Research Center (ERERC) Jiangsu Key Laboratory for Nano Technology National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences Nanjing University national laboratory of solid state microstructures and Department of Physics Nanjing University

Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large scale. The effects of Cl-ions in seawater on the performance of a photoanode have been reported in previous studies. However, few researches have been done on the roles of Cl-ions in a photocathode. Herein, for the first time, we find that Cl-ions in the electrolyte improve the photocurrent of a Si/In2S3photocathode by 50% at-0.6 VRHE. An in-situ X-ray photoelectron spectroscopy（XPS） characterization combined with the time-of-flight secondary-ion mass spectrometry by simulating photoelectrochemical conditions was used to investigate the interface charge transfer mechanism. The results suggest that there is an In2+3S3–x（OH）2xlayer on the surface of In2S3in the phosphate buffer solution（PBS） electrolyte, which plays a role as an interface charge transfer mediator in the Si/In2S3photocathode. The In2+3S3–x（OH）2xsurface layer becomes In2+3S3–x（Cl）2xin the PBS electrolyte with NaCl and accelerates the charge transfer rate at the In2S3/electrolyte interface. These results offer a new concept of regulating interface charge transfer mediator to enhance the performance of photoelectrocatalytic seawater splitting for hydrogen production.

关键词： solar hydrogen production interface charge transfer mechanism coupled electron and ion transfer in-situ XPS characterization In2+3S3–x(OH)2x surface layer

Fatigue-resistant Hydrogels

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Chemical Research in Chinese Universities 2024年第1期40卷 64-77页

作者： LI Luofei LEI Hai CAO Yi Collaborative Innovation Center of Advanced microstructures National Laboratory of Solid State MicrostructureDepartment of PhysicsNanjing UniversityNanjing 210093P.R.China Department of Physics Zhejiang UniversityHangzhou 310027P.R.China

Hydrogels have been extensively studied for applications in various fields, such as tissue engineering and soft robotics, as determined by their mechanical properties. The mechanical design of hydrogels typically focuses on the modulus, toughness, and deformability. These characteristics play important roles and make great achievements for hydrogel use. In recent years, a growing body of research has concentrated on the fatigue property of hydrogels, which determines their resistance to crack propagation in the networks during cyclic mechanical loads for applications. However, knowledge of hydrogel fatigue behavior remains notably deficient. Here, we present a brief overview of the fatigue behavior of hydrogels, encompassing the general experimental methods to measure the fatigue property and fundamental theoretical calculation models. Then, we highlight multiple strategies to enhance the fatigue resistance of hydrogels. Finally, we present our perspectives on fatigue-resistant hydrogels, outstanding challenges and potential directions for future research.

关键词： Hydrogel Fatigue-resistant Fracture

Machine-learning-assisted efficient reconstruction of the quantum states generated from the Sagnac polarization-entangled photon source

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Chinese Physics B 2024年第8期33卷 50-54页

作者：毛梦辉周唯李新慧杨然龚彦晓祝世宁 national laboratory of solid state microstructures and School of Physics Nanjing UniversityNanjing 210093China Author notes

Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different *** on ML technique,we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon *** properly modeling the target states,a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique,and hence our method reduces the resource consumption without loss of *** demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental ***,the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated *** method could be generalized to estimate other kinds of states,as well as other quantum information tasks.

关键词： machine learning state estimation quantum state tomography polarization-entangled photon source

Balancing the Quantum Speed Limit and Instantaneous Energy Cost in Adiabatic Quantum Evolution

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Chinese Physics Letters 2024年第4期41卷 7-12页

作者：徐建文张宇佳郑文蔡浩阳周浩宇李先科廖绪东张钰李邵雄兰栋谭新生于扬 national laboratory of solid state microstructures School of PhysicsNanjing UniversityNanjing 210093China Shishan laboratory Suzhou Campus of Nanjing UniversitySuzhou 215163China Hefei national laboratory Hefei 230088China

Adiabatic time-optimal quantum controls are extensively used in quantum technologies to break the constraints imposed by short coherence ***,practically it is crucial to consider the trade-off between the quantum evolution speed and instantaneous energy cost of process because of the constraints in the available control ***,we experimentally show that using a transmon qubit that,even in the presence of vanishing energy gaps,it is possible to reach a highly time-optimal adiabatic quantum driving at low energy cost in the whole evolution *** validates the recently derived general solution of the quantum Zermelo navigation problem,paving the way for energy-efficient quantum control which is usually overlooked in conventional speed-up schemes,including the well-known counter-diabatic *** designing the control Hamiltonian based on the quantum speed limit bound quantified by the changing rate of phase in the interaction picture,we reveal the relationship between the quantum speed limit and instantaneous energy ***,we demonstrate fast and high-fidelity quantum adiabatic processes by employing energy-efficient driving strengths,indicating a promising strategy for expanding the applications of time-optimal quantum controls in superconducting quantum circuits.

关键词： process quantum adiabatic

Individual dynamics and local heterogeneity provide a microscopic view of the epidemic spreading

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Chinese Physics B 2024年第5期33卷 656-663页

作者：朱友源沈瑞哲董昊王炜 Kuang Yaming Honors School Nanjing UniversityNanjing 210023China Collaborative Innovation Center of Advanced microstructures National Laboratory of Solid State MicrostructureSchool of PhysicsNanjing UniversityNanjing 210093China Institute for Brain Sciences Nanjing UniversityNanjing 210023China state Key laboratory of Analytical Chemistry for Life Science Nanjing UniversityNanjing 210023China

The COVID-19 pandemic has caused severe global disasters,highlighting the importance of understanding the details and trends of epidemic transmission in order to introduce efficient intervention *** the widely used deterministic compartmental models have qualitatively presented continuous “analytical” insight and captured some transmission features,their treatment usually lacks spatiotemporal ***,we propose a stochastic individual dynamical(SID)model to mimic the random and heterogeneous nature of epidemic *** SID model provides a unifying framework for representing the spatiotemporal variations of epidemic development by tracking the movements of each *** this model,we reproduce the infection curves for COVID-19 cases in different areas globally and find the local dynamics and heterogeneity at the individual level that affect the disease *** macroscopic trend of virus spreading is clearly illustrated from the microscopic perspective,enabling a quantitative assessment of different ***,this model is also applicable to studying stochastic processes at the “meter scale”,e.g.,human society’s collective dynamics.

关键词： Brownian motion epidemic spreading heterogeneity

Mott Gap Filling by Doping Electrons through Depositing One Sub-Monolayer Thin Film of Rb on Ca_(2)CuO_(2)Cl_(2)

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Chinese Physics Letters 2024年第5期41卷 90-96页

作者：李寒王朝晖范圣泰李华州杨欢闻海虎 national laboratory of solid state microstructures and Department of Physics Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Understanding the doping evolution from a Mott insulator to a superconductor probably holds the key to resolve the mystery of unconventional superconductivity in copper oxides. To elucidate the evolution of the electronic state starting from the Mott insulator, we dose the surface of the parent phase Ca_(2)CuO_(2)Cl_(2) by depositing Rb atoms, which are supposed to donate electrons to the CuO_(2) planes underneath. We successfully achieved the Rb sub-monolayer thin films in forming the square lattice. The scanning tunneling microscopy or spectroscopy measurements on the surface show that the Fermi energy is pinned within the Mott gap but close to the edge of the charge transfer band. In addition, an in-gap state appears at the bottom of the upper Hubbard band(UHB), and the Mott gap will be significantly diminished. Combined with the Cl defect and the Rb adatom/cluster results, the electron doping is likely to increase the spectra weight of the UHB for the double occupancy. Our results provide information to understand the electron doping to the parent compound of cuprates.

关键词： doping holds Electron

Supercoiled DNA Minicircles under Double-strand Breaks

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Chinese Journal of Polymer Science 2024年第9期42卷 1353-1359,I0007页

作者： Ye-Peng Qiao Chun-Lai Ren national laboratory of solid state microstructures and Department of Physics Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210093China

Understanding how supercoiled DNA releases intramolecular stress is essential for its functional ***,the molecular mechanism underlying the relaxation process remains insufficiently *** we employed MD simulations based on the oxDNA2 model to investigate the relaxation process of a 336-base pair supercoiled minicircular DNA under double-strand breaks with two fixed *** simulations show that the conformational changes in the DNA occur continuously,with intramolecular stress release happening abruptly only when the DNA chain traverses the breakage *** relaxation process is influenced not only by the separation distance between the fixed ends but also their ***,we observe an inhibitory effect on the relaxation characterized by small angles,where short terminal loops impede DNA conformational adjustments,preserving the supercoiled *** findings elucidate the intricate interplay between DNA conformational change,DNA motion and intramolecular stress release,shedding light on the mechanisms governing the relaxation of supercoiled DNA at the molecular level.

关键词： Supercoiled DNA DNA minicircle DNA relaxation oxDNA model MD simulation

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