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Collective flow and fluid behavior in p/d/^(3)He+Au collisions at√s_(NN)=200 GeV

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Chinese physics C 2024年第10期48卷 185-192页

作者： Zeming Wu Baochi Fu Shujun Zhao Runsheng Liu Huichao Song School of physics Peking UniversityBeijing 100871China Collaborative Innovation center of Quantum Matter Beijing 100871China center for High Energy physics Peking UniversityBeijing 100871China

By varying the intrinsic initial geometry,p/d/^(3)He+Au collisions at the Relativistic Heavy Ion Collider(RHIC)provide a unique opportunity to understand the collective behavior and probe possible sub-nucleon fluctuations in small *** this study,we employed the hybrid model under TRENTo initial conditions to study the collective flow and fluid behavior in p/d/^(3)He+Au *** fine-tuned parameters,iEBE-VISHNU can describe the v_(2)(pT) and v_(3)(pT) data from the PHENIX and STAR ***,for certain parameter sets with initial sub-nucleon fluctuations,the hydrodynamic simulations already go beyond their limits with an average Knudsen number clearly larger than *** calculations demonstrate that,for a meaningful evaluation of the fluid behavior in small systems,model simulations must also pay attention to the validity range of hydrodynamics.

关键词： heavy-ion collisions hydrodynamics collective flow

Superexchange and charge transfer in the nickelate superconductor La_(3)Ni_(2)O_(7) under pressure

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Science China(physics,Mechanics & Astronomy) 2024年第11期67卷 1-8页

作者： Wéi Wú Zhihui Luo Dao-Xin Yao Meng Wang center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSchool of PhysicsSun Yat-sen UniversityGuangzhou 510275China

Recently, a bulk nickelate superconductor La_(3)Ni_(2)O_(7) is discovered at pressures with a remarkable high transition temperature T_(c)~ 80 K. Here, we study a Hubbard model with tight-binding parameters derived from ab initio calculations of La_(3)Ni_(2)O_(7),by employing large scale determinant quantum Monte Carlo and cellular dynamical mean-field theory. Our result suggests that the superexchange couplings in this system are comparable to that of cuprates. The system is a charge transfer insulator as the hole concentration becomes four per site at large Hubbard U. Upon hole doping, two low-energy spin-singlet bands emerge in the system exhibiting distinct correlation properties: while the one composed of the out-of-plane Ni-d_(3z^(2)-r^(2)) and O-p_(z) orbitals demonstrates strong antiferromagnetic correlations and narrow effective bandwidth, the in-plane singlet band consisting of the Ni-d_(x^(2)-y^(2)) and O-p_(x)/p_(y) orbitals is in general more itinerant. Over a broad range of hole doping, the doped holes occupy primarily the d_(x^(2)-y^(2)) and p_(x)/p_(y) orbitals, whereas the d_(3z^(2)-r^(2)) and p_(z) orbitals retain underdoped. We propose an effective t-J model to capture the relevant physics and discuss the implications of our result for comprehending the La_(3)Ni_(2)O_(7) superconductivity.

关键词： superconductivity nickelate superconductors Hubbard model superexchange charge transfer insulator quantum Monte Carlo

The de Haas-van Alphen quantum oscillations in the kagome metal RbTi_(3)Bi_(5)

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Chinese physics B 2024年第10期33卷 356-361页

作者： Zixian Dong Lei Shi Bin Wang Mengwu Huo Xing Huang Chaoxin Huang Peiyue Ma Yunwei Zhang Bing Shen Meng Wang center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSchool of PhysicsSun Yat-Sen UniversityGuangzhou 510275China

The kagome system has attracted great interest in condensed matter physics due to its unique structure that canhost various exotic states such as superconductivity(SC),charge density waves(CDWs)and nontrivial topological *** topological semimetal RbTi_(3)Bi_(5)consisting of a Ti kagome layer shares a similar crystal structure to the topologicalcorrelated materials AV_(3)Sb_(5)(A=K,Rb,Cs)but without the absence of CDW and *** de Haas-van Alphenoscillation measurements are performed on single crystals of RbTi_(3)Bi_(5)to pursue nontrivial topological physics and *** this with theoretical calculations,the detailed Fermi surface topology and band structure are investigated.A two-dimensional Fermi pocket b is revealed with a light effective mass,consistent with the semimetal *** fan diagram of RbTi_(3)Bi_(5)reveals a zero Berry phase for the b oscillation in contrast to that of CsTi_(3)Bi_(5).Theseresults suggest that kagome RbTi_(3)Bi_(5)is a good candidate for exploring nontrivial topological exotic states and topologicalcorrelated physics.

关键词： oscillation Fermi surface band structure

Tunable quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures

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National Science Review 2024年第3期11卷 100-107页

作者： Feng Xue Yusheng Hou Zhe Wang Zhiming Xu Ke He Ruqian Wu Yong Xu Wenhui Duan Beijing Academy of Quantum Information Sciences State Key Laboratory of Low Dimensional Quantum physics Department of Physics Tsinghua University Guangdong Provincial Key Laboratory of Magnetoelectric physics and Devices Center for Neutron Science and Technology School of Physics Sun Yat-sen University State Key Laboratory of Surface physics Key Laboratory of Computational Physical Sciences and Department of PhysicsFudan University Frontier Science center for Quantum Information Department of physics and Astronomy University of California-Irvine Tencent Quantum Laboratory Tencent Technology(Shenzhen)Co.Ltd RIKEN center for Emergent Matter Science(CEMS) Institute for Advanced Study Tsinghua University

The quantum anomalous Hall effect（QAHE） has unique advantages in topotronic applications, but it is still challenging to realize the QAHE with tunable magnetic and topological properties for building functional devices. Through systematic first-principles calculations, we predict that the in-plane magnetization induced QAHE with Chern numbers C = ±1 and the out-of-plane magnetization induced QAHE with high Chern numbers C = ±3 can be realized in a single material candidate, which is composed of van der Waals（vdW）coupled Bi and MnBi2Te4monolayers. The switching between different phases of QAHE can be controlled in multiple ways, such as applying strain or（weak） magnetic field or twisting the vdW materials. The prediction of an experimentally available material system hosting robust, highly tunable QAHE will stimulate great research interest in the field. Our work opens a new avenue for the realization of tunable QAHE and provides a practical material platform for the development of topological electronics.

关键词： quantum anomalous Hall effect topological quantum phase transition van der Waals heterostructures tunable Chern number high Chern number

Single-atomic activation on ZnIn_(2)S_(4)basal planes boosts photocatalytic hydrogen evolution

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Nano Research 2024年第7期17卷 5949-5955页

作者： Jianpeng Cui Ying Wang Luxue Lin Xiaotian Yang Xuyu Luo Shiying Guo Xiaoyong Xu College of physics Science and Technology and Center for Interdisciplinary ResearchYangzhou UniversityYangzhou 225002China

The use of single-atom cocatalysts plays a crucial role in enhancing artificial photocatalysis,where the precise construction of stable and efficient single-atom configuration is essential but remains ***,we report a simple one-step hydrothermal method for preparing single-atomic Mo modified ZnIn_(2)S_(4)(Mo-ZIS)nanosheets as a highly active photocatalytic hydrogen evolution(PHE)*** Mo substituting for portion of In atoms in ZIS nanosheets induces the spatial charge redistribution,which not only promotes the separation of photogenerated charge carriers but also optimizes the Gibbs free energy of adsorbing H*on S atoms at basal *** a result,Mo-ZIS exhibits an impressive PHE rate as high as 6.71 mmol·g^(−1)·h^(−1),over 10 times that of the pristine ZIS,with an apparent quantum efficiency(AQE)up to 38.8%at 420 *** study gains insights into the coordination configuration and electronic modulation resulting from single-atomic decoration,providing mechanistic cognitions for the development of advanced photocatalysts via non-precious metal atomic modification.

关键词： photocatalytic hydrogen evolution ZnIn_(2)S_(4) single-atom activation Gibbs free energy

Domain wall network:A dual solution for gravitational waves and Hubble tension?

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Science China(physics,Mechanics & Astronomy) 2024年第11期67卷 39-46页

作者： Ligong Bian Shuailiang Ge Changhong Li Jing Shu Junchao Zong Department of physics and Chongqing Key Laboratory for Strongly Coupled physics Chongqing UniversityChongqing 401331China center for High Energy physics Peking UniversityBeijing 100871China School of physics and State Key Laboratory of Nuclear physics and Technology Peking UniversityBeijing 100871China Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan ProvinceSchool of Physics and AstronomyYunnan UniversityKunming 650091China Beijing Laser Acceleration Innovation center Beijing 101400China Department of physics Nanjing UniversityNanjing 210093China CAS Key Laboratory of Theoretical physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China

We explore the possibility that domain wall networks generate the stochastic gravitational wave background(SGWB) observed as a strong common power-law process in the Data Release-2 of Parkes Pulsar Timing Array. We find that a broad range of parameters, specifically wall tension around σ_(DW)^(29-414 TeV)^(3) and wall-decay temperature within T_(d) ~ 20-257 MeV, can explain this phenomenon at a 68% credible level. Meanwhile, the same parameters could ease the Hubble tension if particles from these domain wall networks decay into dark radiation. We establish a direct analytical relationship, ΩGW(f_(p), T_(0))h^(2)~ Ω_(rad)h^(2)(Ω_νΩN_(eff))^(2),to illustrate this coincidence, underlining its importance in the underlying physics and potential applicability to a wider range of models and data. Conversely, if the common power-law process is not attributed to domain wall networks, our findings impose tight limits on the wall tension and decay temperature.

关键词： domain wall gravitational waves Hubble tension

Manipulation of band gap in 1T-TiSe_(2) via rubidium deposition

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Chinese physics B 2024年第8期33卷 102-106页

作者：欧仪陈磊信子鸣任宇靖袁鹏浩王政国朱玉陈景芝张焱 International center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China

The 1T-TiSe_(2) is a two-dimensional charge-density-wave(CDW)material that attracts great interest.A small band gap locates at the Fermi level separating the Ti d-bands and Se p-bands,which makes 1T-TiSe_(2) a promising candidate for realizing excitonic ***,we studied the band gap in 1T-TiSe_(2) using angle-resolved photoemission spectroscopy(ARPES).Instead of only focusing on the in-plane band dispersions,we obtained the detailed band dispersions of both conduction and valance bands along the out-of-plane *** found that the conduction and valance bands split into multiple sub-bands in the CDW state due to band *** a result,the band gap between the Ti d-bands and Se p-bands reduces to~25 meV and becomes a direct gap in the CDW *** intriguingly,such band gap can be further reduced by the rubidium *** band structure becomes semimetallic in the rubidium-doped ***,exotic gapless behaviors were observed at the p-d band *** result characterized the band gap of 1T-TiSe_(2) in three-dimensional Brillouin zone with unpreceded *** also suggests a closing of band gap or a potential band inversion in 1T-TiSe_(2) driven by rubidium deposition.

关键词： angle-resolved photoemission spectroscopy metal–insulator transition transition metal dichalcogenides

In situ generation of oxyanions-decorated cobalt(nickel)oxyhydroxide catalyst with high corrosion resistance for stable and efficient seawater oxidation

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Journal of Energy Chemistry 2024年第7期94卷 508-516页

作者： Fengting Luo Pei Yu Jueting Xiang Junjie Jiang Shijian Chen Chongqing Key Laboratory of Interface physics in Energy Conversion College of PhysicsChongqing UniversityChongqing 401331China center of Modern physics Institute for Smart City of Chongqing University in LiyangLiyang 213300JiangsuChina

The development of efficient and robust anode materials for stable alkaline seawater electrolysis is severely limited by chlorine evolution reaction and chloride ***,the sulfur-doped cobalt-nickel bimetallic phosphides(CoNiPS)are specifically designed as a pre-catalyst for navigating a surface reconstruction to fabricate the anions(PO^(3-)_(4) and SO^(2-)_(4))-decorated Co(Ni)OOH catalyst(R-CoNiPS)with exceptional durability and high activity for stable alkaline seawater oxidation(ASO).Various experiment techniques together with theoretical simulations both demonstrate that the in situ-generated PO^(3-)_(4) and SO^(2-)_(4) anions on catalyst surface can improve the oxygen evolution reaction(OER)activity,regulating and stabilizing the catalytic active species Co(Ni)OOH,as well as make a critical role in inhibiting the adsorp-tion of chloride ions and extending the service life of ***,this R-CoNiPS electrode exhi-bits superb OER activity toward AsO and stands out among the non-precious ASO electrocatalysts reported recently,requiring low overpotentials of 420 and 440 mV to attain large current densities of 500 and 1000 mA cm^(-2) in an alkaline natural seawater electrolyte,***,the catalyst displays a negligible chloride corrosion at room temperature during ASO operation(>200 h)at 500 mA cm^(-2).This work opens up a new viewpoint for designing high-activity and durable electrocata-lystsforseawaterelectrolysis.

关键词： Seawater electrolysis Anions Oxygen evolution reaction Chloride corrosion

A pseudoclassical theory for the wavepacket dynamics of the kicked rotor model

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Science China(physics,Mechanics & Astronomy) 2024年第3期67卷 34-43页

作者： Zhixing Zou Jiao Wang Department of physics and Key Laboratory of Low Dimensional Condensed Matter physics(Department of Education of Fujian Province) Xiamen UniversityXiamen 361005China Lanzhou center for Theoretical physics Lanzhou UniversityLanzhou 730000China

In this study, we propose a generalized pseudoclassical theory for the kicked rotor model in an attempt to discern the footprints of the classical dynamics in the deep quantum regime. Compared with the previous pseudoclassical theory that applies only in the neighborhoods of the lowest two quantum resonances, the proposed theory is applicable in the neighborhoods of all quantum resonances in principle by considering the quantum effect of the free rotation at a quantum resonance. In particular, it is confirmed by simulations that the quantum wavepacket dynamics can be successfully forecasted based on the generalized pseudoclassical dynamics, offering an intriguing example where it is feasible to bridge the dynamics in the deep quantum regime to the classical dynamics. The application of the generalized pseudoclassical theory to the PT-symmetric kicked rotor is also discussed.

关键词： quantum-classical correspondence kicked rotor model pseudoclassical theory wavepacket dynamics