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Constraints on holographic QCD phase transitions from PTA observations

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Science China(physics,Mechanics & Astronomy) 2024年

作者： Song He Li Li Sai Wang Shao-Jiang Wang Center for Theoretical physics and College of physics Jilin University School of Physical Science and Technology Ningbo University max Planck institute for Gravitational physics (Albert Einstein institute) CAS Key Laboratory of Theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences School of Fundamental physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences (UCAS) School of Physical Sciences University of Chinese Academy of Sciences (UCAS) Theoretical physics Division Institute of High Energy Physics Chinese Academy of Sciences

The underlying physics of QCD phase transition in the early Universe remains largely unknown due to its strong-coupling nature during the quark-gluon plasma/hadron gas transition, yet a holographic model has been proposed to quantitatively fit the lattice QCD data while with its duration of the first-order phase transition(FoPT) left undetermined. At specific baryon chemical potential, the first-order QCD phase transition agrees with the observational constraint of baryon asymmetry. It, therefore, provides a scenario for phase transition gravitational waves(GWs) within the standard model of particle physics. If these background GWs could contribute dominantly to the recently claimed common-spectrum red noise from pulsar timing array(PTA) observations, the duration of this FoPT can be well constrained, and the associated primordial black holes are still allowed by current observations.

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Experimental observation of the significant difference between surface and bulk Kondo processes in Kondo lattice YbCu_(2)Si_(2)

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Science China(physics,Mechanics & Astronomy) 2024年第4期67卷 154-160页

作者： Yin-Zou Zhao Jiao-Jiao Song Qi-Yi Wu Hao Liu Chen Zhang Bo Chen Hong-Yi Zhang Zhen-Hua Chen Yao-Bo Huang Xue-Qing Ye Ya-Hua Yuan Yu-Xia Duan Jun He Jian-Qiao Meng School of physics Central South UniversityChangsha 410083China Shanghai institute of Applied physics Chinese Academy of SciencesShanghai 201204China

Synchrotron-based angle-resolved photoemission spectroscopy was employed to investigate the temperature evolution of the Yb 4 f spectral for surface and bulk in the Kondo lattice YbCu_(2)Si_(2).Our study quantitatively distinguishes between the surface and bulk hybridization processes,revealing that the onset temperatures for both surface and bulk hybridization processes are significantly higher than the Kondo ***,we found that the effective surface Kondo temperature is much lower than that of the *** findings offer valuable insights into the understanding of heavy fermion physics.

关键词： Kondo lattice angle-resolved photoemission spectroscopy electronic structure hybridization surface state

Cathodic corrosion as a facile and universal method for scalable preparation of powdery single atom electrocatalysts

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Nano Research 2024年第6期17卷 4943-4950页

作者： Rui Li Xiayan Yan Meng Liu Qingkai Zhao Jie Du Xinxin Tan Jingwen Ba Rongguang Zeng Wenhua Luo Jingsong Xu institute of Materials China Academy of Engineering PhysicsJiangyou 621907China Science and Technology on Surface physics and Chemistry Laboratory Jiangyou 621908China

Top-down strategy has been widely applied for synthesis of metal single atom catalysts(SACs)via converting metal nanoparticles or bulk metals into atomically dispersed ***,we report a simple electrochemical atomic migration strategy for top-down synthesis of SACs via a facile cathodic corrosion process without involving high temperature or harsh *** of metal nanoparticles on cathode are firstly disbanded under high negative voltage,and emitted into the electrolyte in the form of atomic metal anions in Zintl *** escaped atomically dispersed metal species are then oxidized by water molecules and captured by the defects on the pre-added nitrogen doped carbon carriers in the *** cathodic corrosion strategy is confirmed to be suitable for scalable synthesis of kinds of metal SACs(e.g.,Pt,Pd,and Ir)on doped carbon ***,the as-prepared nitrogen doped carbon powder supported Pt SACs exhibit superior catalytic activity toward hydrogen evolution reaction(HER)with a low overpotential of 0.024 V at 10 mA·cm^(−2)and a low Tafel slope of 29.7 mV·dec^(−1)as well as a long-term durability.

关键词： cathodic corrosion top-down strategy powdery single atom catalysts hydrogen evolution reaction scalable synthesis

Exploring hidden-charm and hidden-strange hexaquark states from lattice QCD

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Science China(physics,Mechanics & Astronomy) 2024年第1期67卷 30-37页

作者： Hang Liu Jinchen He Liuming Liu Peng Sun Wei Wang Yi-Bo Yang Qi-An Zhang INPAC Key Laboratory for Particle Astrophysics and Cosmology(MOE)Shanghai Key Laboratory for Particle Physics and CosmologySchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Maryland Center for Fundamental physics Department of PhysicsUniversity of MarylandCollege ParkMaryland 20742USA institute of Modern physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Department of physics and institute of Theoretical physics Nanjing Normal UniversityNanjing 210023China Southern Center for Nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China CAS Key Laboratory of Theoretical physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Fundamental physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China International Centre for Theoretical physics Asia-Pacific Beijing 100049/Hangzhou 310024China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of physics Beihang UniversityBeijing 102206China

Based on five different ensembles of newly generated(2+1)-flavor configurations with pion mass of approximately mπ■(140-310)MeV,we present a lattice analysis of hidden-charm and hidden-strange hexaquarks with the quark content■.The correlation matrices of two types of operators with JPC=0++,0-+,1++and 1--are simulated to extract the masses of the hexaquark candidates,which are subsequently extrapolated to the physical pion mass and continuum *** results indicate that ground state masses are below the■threshold and provide a characteristic signal for the experimental discovery of hexaquark candidates,which may enrich the versatile structure of multiquarks;moreover,it is an indispensable step to decipher the nonperturbative nature of the fundamental interactions of quarks and gluons.

关键词： quantum chromodynamics lattice QCD multiquark states

A deep learning interatomic potential suitable for simulating radiation damage in bulk tungsten

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Tungsten 2024年第2期6卷 304-322页

作者： Chang-Jie Ding Ya-Wei Lei Xiao-Yang Wang Xiao-Lin Li Xiang-Yan Li Yan-Ge Zhang Yi-Chun Xu Chang-Song Liu Xue-Bang Wu Key Laboratory of Materials physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China Science Island University of Science and Technology of ChinaHefei 230026China Laboratory of Computational physics Institute of Applied Physics and Computational MathematicsBeijing 100088China

So far, it has been a challenge for existing interatomic potentials to accurately describe a wide range of physical properties and maintain reasonable efficiency. In this work, we develop an interatomic potential for simulating radiation damage in body-centered cubic tungsten by employing deep potential, a neural network-based deep learning model for representing the potential energy surface. The resulting potential predicts a variety of physical properties consistent with first-principles calculations, including phonon spectrum, thermal expansion, generalized stacking fault energies, energetics of free surfaces, point defects, vacancy clusters, and prismatic dislocation loops. Specifically, we investigated the elasticity-related properties of prismatic dislocation loops, i.e., their dipole tensors, relaxation volumes, and elastic interaction energies. This potential is found to predict the maximal elastic interaction energy between two 1/2 loops better than previous potentials, with a relative error of only 7.6%. The predicted threshold displacement energies are in reasonable agreement with experimental results, with an average of 128 eV. The efficiency of the present potential is also comparable to the tabulated gaussian approximation potentials and modified embedded atom method potentials, meanwhile, can be further accelerated by graphical processing units. Extensive benchmark tests indicate that this potential has a relatively good balance between accuracy, transferability, and efficiency.

关键词： Machine learning Deep learning Interatomic potential Radiation damage Tungsten

Electricity resonance-induced phase transition of water confined in nanochannels

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Communications in Theoretical physics 2024年第5期76卷 159-165页

作者： Yunqiu Ma Zhigao Zhao Shaoqian Hao Jianlong Kou Jiang-Xing Chen institute of Condensed Matter physics Zhejiang Institute of Photoelectronics&Zhejiang Institute for Advanced Light SourceZhejiang Normal UniversityJinhua 321004China Department of physics Inner Mongolia UniversityHohhot 010021China Department of physics Hangzhou Normal UniversityHangzhou 311121China

The phase transition of water molecules in nanochannels under varying external electric fields is studied by molecular dynamics *** is found that the phase transition of water molecules in nanochannels occurs by changing the frequency of the varying electric *** molecules maintain the ice phase when the frequency of the varying electric field is less than 16 THz or greater than 30 THz,and they completely melt when the frequency of the varying electric field is 24 *** phenomenon is attributed to the breaking of hydrogen bonds when the frequency of the varying electric field is close to their inherent resonant ***,the study demonstrates that the critical frequency varies with the confinement *** new mechanism of regulating the phase transition of water molecules in nanochannels revealed in this study provides a perspective for further understanding of the phase transition of water molecules in nanochannels,and has great application potential in preventing icing and deicing.

关键词： electricity resonance phase transition water molecules molecular dynamics simulations

Structure,ferroelectric,and enhanced fatigue properties of sol–gel-processed new Bi-based perovskite thin films of Bi(Cu_(1/2)Ti_(1/2))O_(3)–PbTiO_(3)

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Chinese physics B 2024年第5期33卷 608-615页

作者：宋伟宾席国强潘昭刘锦叶旭斌刘哲宏王潇单鹏飞张林兴鲁年鹏樊龙龙秦晓梅龙有文 Department of physics Shanghai Normal UniversityShanghai 200234China Beijing National Laboratory for Condensed Matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China institute for Advanced Materials Technology University of Science and Technology BeijingBeijing 100083China Songshan Lake Materials Laboratory Dongguan 523808China institute of High Energy physics Chinese Academy of SciencesBeijing 100049China

Bi-based perovskite ferroelectric thin films have wide applications in electronic devices due to their excellent ferroelectric *** Bi-based perovskite thin films Bi(Cu_(1/2)Ti_(1/2))O_(3)–PbTiO_(3)(BCT–PT) are deposited on Pt(111)/Ti/SiO_(2)/Si substrates in the present study by the traditional sol–gel *** structures and related ferroelectric and fatigue characteristics are studied *** BCT–PT thin films exhibit good crystallization within the phase-pure perovskite structure,besides,they have a predominant(100) orientation together with a dense and homogeneous *** remnant polarization(2P_(r)) values at 30 μC/cm^(2) and 16 μC/cm^(2) are observed in 0.1BCT–0.9PT and 0.2BCT–0.8PT thin films,*** intriguingly,although the polarization values are not so high,0.2BCT–0.8PT thin films show outstanding polarization fatigue properties,with a high switchable polarization of 93.6% of the starting values after 10^(8) cycles,indicating promising applications in ferroelectric memories.

关键词： ferroelectric thin films perovskite PbTiO_(3)-BiMeO_(3)

Interlayer Magnetic Interaction in the CrI_(3)/CrSe_(2) Heterostructure

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Chinese physics Letters 2024年第5期41卷 85-89页

作者：王秋皓倪美燕李淑静郑法伟路洪艳张平 School of physics and Physical Engineering Qufu Normal UniversityQufu 273165China Center for Quantum physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and MeasurementSchool of PhysicsBeijing Institute of TechnologyBeijing 100081China Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of TechnologyBeijing 100081China College of Mathematics and physics Beijing University of Chemical TechnologyBeijing 100029China institute of Applied physics and Computational Mathematics Beijing 100088China

Based on first-principles calculations, we systematically study the stacking energy and interlayer magnetic interaction of the heterobilayer composed of CrI_(3) and CrSe_(2) monolayers. It is found that the stacking order plays a crucial role in the interlayer magnetic coupling. Among all possible stacking structures, the AA-stacking is the most stable heterostructure, exhibiting interlayer antiferromagnetic interactions. Interestingly, the interlayer magnetic interaction can be effectively tuned by biaxial strain. A 4.3% compressive strain would result in a ferromagnetic interlayer interaction in all stacking orders. These results reveal the magnetic properties of CrI_(3)/CrSe_(2) heterostructure, which is expected to be applied to spintronic devices.

关键词： strain stacking interlayer

First-principles study of structural and electronic properties of multiferroic oxide Mn_(3)TeO_(6) under high pressure

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Chinese physics B 2024年第7期33卷 448-454页

作者：潘小龙王豪柳雷陈向荣耿华运 College of physics Sichuan UniversityChengdu 610065China National Key Laboratory of Shock Wave and Detonation physics Institute of Fluid PhysicsChina Academy of Engineering PhysicsMianyang 621900China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

Mn_(3)TeO_(6)(MTO) has been experimentally found to adopt a P2_(1)/In structure under high pressure,which exhibits a significantly smaller band gap compared to the atmospheric R3 *** this study,we systematically investigate the magnetism,structural phase transition,and electronic properties of MTO under high pressure through first-principles *** R3 and P2_(1)/n phases of MTO are antiferromagnetic at zero *** R3 phase transforms to the P2_(1)/n phase at 7.5 8 GPa,accompanied by a considerable volume collapse of about 6.47%.Employing the accurate method that combines DFT+U/and GW,the calculated band gap of R3 phase at zero pressure is very close to the experimental values,while that of the P2_(1)/n phase is significantly *** main reason for this difference is that the experimental study incorrectly used the Kubelka-Munk plot for the indirect band gap to obtain the band gap of the P2_(1)/n phase instead of the Kubelka-Munk plot for the direct band ***,our study reveals that the transition from the R3 phase to the P2_(1)/n phase is accompanied by a slight reduction in the band gap.

关键词： magnetism phase transition band gap high pressure