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Polarization control of above-threshold ionization spectrum in elliptically polarized two-color laser fields

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Chinese physics B 2024年第4期33卷 136-144页

作者：金发成杨慧慧宋晓红李飞杜玲玲薛红杰魏丽敏白悦刘浩翔王兵兵杨玮枫 Faculty of Science Xi'an Aeronautical InstituteXi'an 710077China School of physics and Optoelectronic Engineering Hainan UniversityHaikou 570288China Center for Theoretical physics Hainan UniversityHaikou 570288China laboratory of Optical physics Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China College of Science Shantou UniversityShantou 515063China University of Chinese Academy of Sciences Beijing 100049China

We study the above-threshold ionization(ATI)process of atoms exposed to fundamental and high-frequency lasers with arbitrary ellipticity by applying the frequency-domain *** is found that the angular-resolved ATI spectrum is sensitive to ellipticities of two lasers and emitted angles of the *** for the photon energy of the highfrequency laser more than atomic ionization potential,the width of plateau tends to a constant with increasing ellipticity of fundamental field,the dip structure disappears with increasing ellipticity of the high-frequency *** the help of the quantum channel analysis,it is shown that the angular distribution depends mainly on the ellipticity of high-frequency field in the case that its frequency is ***,one can see that the maximal and minimal energies in quantum numerical results are in good agreement with the classical *** investigation may provide theoretical support for experimental research on polarization control of ionization in elliptically polarized two-color laser fields.

关键词： above-threshold ionization two-color laser polarization control

Classification of high-ordered topological nodes towards Moiré flat bands in twisted bilayers

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Science China(physics,Mechanics & Astronomy) 2024年第9期67卷 133-147页

作者： Fan Cui Congcong Le Qiang Zhang Xianxin Wu Jiangping Hu Ching-Kai Chiu beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China RIKEN Interdisciplinary Theoretical and Mathematical Sciences(iTHEMS) Wako 351-0198Japan CAS Key laboratory of Theoretical physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Kavli Institute of Theoretical Sciences University of Chinese Academy of SciencesBeijing 100190China New Cornerstone Science laboratory Beijing 100190China

At magic twisted angles,Dirac cones in twisted bilayer graphene(TBG)can evolve into flat bands,serving as a critical playground for the study of strongly correlated *** chiral symmetry is introduced,rigorous mathematical proof confirms that the flat bands are locked at zero energy in the entire Moiré Brillouin zone(BZ).Yet,TBG is not the sole platform that exhibits this absolute band *** to this flatness phenomenon are topological nodes and their specific locations in the *** this study,considering twisted bilayer systems that preserve chiral symmetry,we classify various ordered topological nodes in base layers and all possible node locations across different ***,we constrain the node locations to rotational centers,such as Γ and M points,to ensure the interlayer coupling retains equal strength in all *** this classification as a foundation,we systematically identify the conditions under which Moiré flat bands ***,through the extension of holomorphic functions,we provide proof that flat bands are locked at zero energy,shedding light on the origin of the band ***,beyond Dirac cones,numerous twisted bilayer nodal platforms can host flat bands with a degeneracy number of more than two,such as four-fold,six-fold,and *** multiplicity of degeneracy in flat bands might unveil more complex and enriched correlation physics.

关键词： twisted bilayer systems high-ordered topological nodes Moriéflat bands high degeneracy

Prediction of impurity spectrum function by deep learning algorithm

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Chinese physics B 2024年第5期33卷 52-63页

作者：刘婷韩榕生陈亮 School of Mathematics and physics North China Electric Power UniversityBeijing 102206China Institute of condensed matter physics North China Electric Power UniversityBeijing 102206China Hebei Key laboratory of physics and Energy Technology North China Electric Power UniversityBaoding 071003China

By using the numerical renormalization group(NRG)method,we construct a large dataset with about one million spectral functions of the Anderson quantum impurity *** dataset contains the density of states(DOS)of the host material,the strength of Coulomb interaction between on-site electrons(U),and the hybridization between the host material and the impurity site(Γ).The continued DOS and spectral functions are stored with Chebyshev coefficients and wavelet functions,*** this dataset,we build seven different machine learning networks to predict the spectral function from the input data,DOS,U,andΓ.Three different evaluation indexes,mean absolute error(MAE),relative error(RE)and root mean square error(RMSE),are used to analyze the prediction abilities of different network *** analysis shows that,for the two kinds of widely used recurrent neural networks(RNNs),gate recurrent unit(GRU)has better performance than the long short term memory(LSTM)network.A combination of bidirectional GRU(BiGRU)and GRU has the best performance among GRU,BiGRU,LSTM,and *** MAE peak of BiGRU+GRU reaches *** have also tested a one-dimensional convolutional neural network(1DCNN)with 20 hidden layers and a residual neural network(ResNet),we find that the 1DCNN has almost the same performance of the BiGRU+GRU network for the original dataset,while the robustness testing seems to be a little weak than BiGRU+GRU when we test all these models on two other independent *** ResNet has the worst performance among all the seven network *** datasets presented in this paper,including the large data set of the spectral function of Anderson quantum impurity model,are openly available at https://***/10.57760/sciencedb.j00113.00192.

关键词： machine learning Anderson impurity model spectral function

Layer-Valley Hall Effect under Inversion and Time-Reversal Symmetries

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Chinese physics Letters 2024年第6期41卷 88-97页

作者：赵交交刘贵斌陈鹏姚裕贵张广宇杜罗军 beijing national laboratory for condensed matter physics and Key Laboratory for Nanoscale Physics and DevicesInstitute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Centre for Quantum physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of TechnologyBeijing 100081China beijing Key Lab of Nanophotonics&Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of TechnologyBeijing 100081China Schoolof Microelectronics Southern University of Science and TechnologyShenzhen 518055China Songshan Lake Materials laboratory Dongguan 523808China

Hall effects have been the central paradigms in modern physics,materials science and practical applications,and have led to many exciting breakthroughs,including the discovery of topological Chern invariants and the revolution of metrological resistance *** date,the Hall effects have mainly focused on a single degree of freedom(Do F),and most of them require the breaking of spatial-inversion and/or time-reversal *** we demonstrate a new type of Hall effect,i.e.,layer-valley Hall effect,based on a combined layer-valley Do F characterized by the product of layer and valley *** layer-valley Hall effect has a quantum origin arising from the layer-valley contrasting Berry curvature,and can occur in nonmagnetic centrosymmetric crystals with both spatial-inversion and time-reversal symmetries,transcending the symmetry constraints of single Do F Hall effect based on the constituent layer or valley ***,the layer-valley Hall effect is highly tunable and shows a W-shaped pattern in response to the out-of-plane electric ***,we discuss the potential detection approaches and material-specific design principles of layer-valley Hall *** results demonstrate novel Hall physics and open up exotic paradigms for new research direction of layer-valleytronics that exploits the quantum nature of the coupled layer-valley DoF.

关键词： quantum Inversion curvature

Spin gap in quasi-one-dimensional S=3/2 antiferromagnet CoTi2O5

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Chinese physics B 2024年第3期33卷 609-617页

作者：徐浩航刘庆元辛潮申沁鑫罗军周睿程金光刘健陶玲玲刘志国霍明学王先杰隋郁 School of physics Harbin Institute of TechnologyHarbin 150001China School of Science Changchun University of Science and TechnologyChangchun 130022China beijing national laboratory for condensed matter physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190China laboratory for Space Environment and Physical Sciences Harbin Institute of TechnologyHarbin 150001China Southwest Institute of Applied Magnetics Mianyang 621000China

Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation *** we demonstrate that a spin gap exists in the quasi-1D Heisenberg antiferromagnet CoTi2O5 with highly ordered Co2+/Ti4+occupation,in which the Co2+ions with S=3/2 form a 1D spin chain along the ***2O5 undergoes an antiferromagnetic transition at TN~24 K and exhibits obvious anisotropic magnetic susceptibility even in the paramagnetic *** a gapless magnetic ground state is usually expected in a quasi-1D Heisenberg antiferromagnet with half-integer spins,by analyzing the specific heat,the thermal conductivity,and the spin-lattice relaxation rate(1/T1)as a function of temperature,we found that a spin gap is opened in the spin-excitation spectrum of CoTi2O5 around TN,manifested by the rapid decrease of magnetic specific heat to zero,the double-peak characteristic in thermal conductivity,and the exponential decay of 1/T1 below *** the magnetic measurements and the first-principles calculations results indicate that there is spin-orbit coupling in CoTi2O5,which induces the magnetic anisotropy in CoTi2O5,and then opens the spin gap at low temperature.

关键词： quasi-one-dimensional antiferromagnet magnetic anisotropy spin gap

Photo-induced Intramolecular Charge Transfer in Strained Organic Cage Containing Orthogonally Arranged Donors and Acceptors

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CCS Chemistry 2024年第8期6卷 1920-1928页

作者： Jingxuan Yang Run Shi Liang-Liang Mao Hongyan Xiao Yi Zeng Guohong Liao Yuxiang Weng Xu-Bing Li Jiaqi Zhao Yunxuan Zhao Tierui Zhang Chen-Ho Tung Li-Zhu Wu Huan Cong Key laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190 Key laboratory of Bio-Inspired Materials and Interfacial Science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190 beijing national laboratory for condensed matter physics Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190 University of Chinese Academy of Sciences Beijing 100049 Binzhou Institute of Technology Weiqiao-UCAS Science and Technology ParkBinzhou CityShandong 256606 Songshan Lake Materials laboratory DongguanGuangdong 523808

Designing and creating molecular structures with precisely organized organic chromophores as donors and acceptors are critical for exploring photo-induced charge transfer *** and acceptor moieties can be incorporated to the confined skeletons of organic cages,thereby offering opportunities tomanipulate excited state characters for the development of novel photofunctional ***,we present the convergent synthesis and photophysical characterizations of an organic cage with anisotropic *** strained and rigid cage can be concisely prepared by connecting two distinct macrocycles through axial stacking strategy,featuring triarylamine and amide moieties as separate donors and acceptors,***-state and time-resolved spectra reveal photo-induced through-space intramolecular charge transfer and long-lived charge separation,thereby verifying the cage’s photocatalytic utility for efficient hydrogen production.

关键词： organic cage macrocycles photoinduced charge transfer through-space photocatalytic hydrogen evolution

Probing phase transition of band topology via radiation topology

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Photonics Research 2024年第6期12卷 1150-1157页

作者： CHANG-YIN JI WENZE LAN PENG FU GANG WANG CHANGZHI GU YELIANG WANG JIAFANG LI YUGUI YAO BAOLI LIU Key laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE) Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic Systemsand School of PhysicsBeijing Institute of TechnologyBeijing 100081China School of Integrated Circuits and Electronics MIIT Key Laboratory for Low-Dimensional Quantum Structure and DevicesBeijing Institute of TechnologyBeijing 100081China beijing national laboratory for condensed matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological Quantum Computation CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China

Topological photonics has received extensive attention from researchers because it provides brand new physical principles to manipulate *** topology is characterized using the Berry phase defined by Bloch *** now,the scheme for experimentally probing the topological phase transition of band topology has always been relatively lacking in topological ***,radiation topology can be aroused by the far-field polarization singularities of Bloch states,which is described by the Stokes *** such two types of topologies are both related to Bloch states on the band structures,it is rather surprising that their development is almost ***,in optical analogs of the quantum spin Hall effects(QSHEs)and Su-Schrieffer-Heeger model,we reveal the correlation between the phase transition of band topology and radiation topology and then demonstrate that the radiation topology can be employed to study the band topological *** experimentally demonstrate such an intriguing phenomenon in optical analogs of *** findings not only provide an insightful understanding of band topology and radiation topology,but also can serve as a route to manipulate light.

关键词： transition topology topological

Low Gilbert damping in Bi/In-doped YIG thin films with giant Faraday effect

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Chinese physics B 2024年第10期33卷 419-426页

作者： Jin Zhan Yi Wang Xianjie Wang Hanxu Zhang Senyin Zhu Lingli Zhang Lingling Tao Yu Sui Wenqing He Caihua Wan Xiufeng Han V.I.Belotelov Bo Song School of physics Harbin Institute of TechnologyHarbin 150001China beijing national laboratory for condensed matter physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190China Russian Quantum Center Moscow 119991Russia national Key laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150001China Zhengzhou Research Institute Harbin Institute of TechnologyZhengzhou 450046China Frontiers Science Center for matter Behave in Space Environment Harbin Institute of TechnologyHarbin 150001China

Magnetic films with low Gilbert damping are crucial for magnonic devices,which provide a promising platform forrealizing ultralow-energy *** this study,low Gilbert damping and coercive field were observed in Bi/In-dopedyttrium iron garnet(BiIn:YIG)thin *** BiIn:YIG(444)films were deposited onto different substrates using pulsedlaser *** coercivity(<1 Oe)with saturation magnetization of 125.09 emu/cc was achieved along the in-planedirection of BiIn:YIG *** values of Gilbert damping and inhomogeneous broadening of ferromagnetic resonance inBiIn:YIG films were obtained to be as low as 4.05×10^(-4)and 5.62 Oe,*** addition to low damping,the giantFaraday rotation angles(up to 2.9×10^(4)deg/cm)were also observed in the BiIn:YIG *** modifying the magneticstructure and coupling effect between Bi^(3+)and Fe^(3+)of Bi:YIG,doped In^(3+)plays a key role on variation of the *** low damping and giant Faraday effect made the BiIn:YIG film an appealing candidate for magnonic andmagneto-optical devices.

关键词： magnonic device Gilbert damping Faraday effect

Surface doping manipulation of the insulating ground states in Ta_(2)Pd_(3)Te_(5) and Ta_(2)Ni_(3)Te_(5)

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Chinese physics B 2024年第6期33卷 88-93页

作者：江北姚静宇闫大禹郭照芃屈歌星邓修同黄耀波丁洪石友国王志俊钱天 beijing national laboratory for condensed matter physics and Institute of physics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Songshan Lake Materials laboratory Dongguan 523808China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China Tsung-Dao Lee Institute New Cornerstone Science Laboratoryand School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 201210China Hefei national laboratory Hefei 230088China

Manipulating emergent quantum phenomena is a key issue for understanding the underlying physics and contributing to possible *** we study the evolution of insulating ground states of Ta_(2)Pu_(3)Te_(5) and Ta_(2)Ni_(3)Te_(5) under in-situ surface potassium deposition via angle-resolved photoemission *** results confirm the excitonic insulator character of Ta_(2)d_(3)Te_(5).Upon surface doping,the size of its global gap decreases *** a deposition time of more than 7 min,the potassium atoms induce a metal-insulator phase transition and make the system recover to a normal *** contrast,our results show that the isostructural compound Ta_(2)Ni_(3)Te_(5) is a conventional *** size of its global gap decreases upon surface doping,but persists positive throughout the doping *** results not only confirm the excitonic origin of the band gap in Ta_(2)Pd_(3)Te_(5),but also offer an effective method for designing functional quantum devices in the future.

关键词： excitonic insulator metal–insulator phase transition surface doping angle-resolved photoemission spectroscopy