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中国科学:物理学 力学 天文学（英文版）
中国科学:物理学 力学 天文学（英文版）

周光召

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中国科学:物理学 力学 天文学（英文版）/Journal Science China(Physics, Mechanics&Astronomy)CSCDCSTPCDEISCI
查看更多>>《中国科学》是中国科学院主办、中国科学杂志社出版的自然科学专业性学术刊物。《中国科学》任务是反映中国自然科学各学科中的最新科研成果，以促进国内外的学术交流。《中国科学》以论文形式报道中国基础研究和应用研究方面具有创造性的、高水平的和有重要意义的科研成果。在国际学术界，《中国科学》作为代表中国最高水平的学术刊物也受到高度重视。国际上最具有权威的检索刊物SCI，多年来一直收录《中国科学》的论文。1999年《中国科学》夺得国家期刊奖的第一名。
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    Finite-size-induced non-Hermitian phase transitions in real space

    Hongfei WangBiye XieWei Ren
    105-111页
    查看更多>>摘要：While non-Hermiticity provokes intriguing phenomena without Hermitian counterparts,e.g.,the skin effect and the breakdown of bulk-boundary correspondence,attracting extensive attention both in fundamental physics and device engineering,the role of finite sizes therein remains elusive.Here,we propose a class of finite-size-induced non-Hermitian phase transitions,relying upon higher-order topological invariants associated with real-space wave functions.The phase diagrams for general non-Hermitian chiral models are further acquired to demonstrate our topological definition.Such phase transitions are elucidated qualitatively by an effective intercell coupling alteration that depends on finite sizes in respective directions.Besides,we mimic these phenomena by analogizing the circuit Laplacian in finite-size electric circuits with nonreciprocal couplings.The resultant admittance spectra agree with our theoretical predictions.Our findings shed light on the finite-size mechanism of non-Hermitian topological phase transitions and pave the way for applications in switching and sensing.
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    Annealing-induced long-range charge density wave order in magnetic kagome FeGe:Fluctuations and disordered structure

    Chenfei ShiYi LiuBishal Baran MaityQi Wang...
    112-121页
    查看更多>>摘要：Charge density wave(CDW)in kagome materials with the geometric frustration is able to carry unconventional characteristics.Recently,a CDW has been observed below the antiferromagnetic order in kagome FeGe,in which magnetism and CDW are intertwined to form an emergent quantum ground state.However,the CDW is only short-ranged and the structural modulation originating from it has yet to be determined experimentally.Here we realize a long-range CDW order by post-annealing process,and resolve the structure model through single crystal X-ray diffraction.Occupational disorder of Ge resulting from short-range CDW correlations above TCDW is identified from structure refinements.The partial dimerization of Ge along the c axis is unveiled to be the dominant distortion for the CDW.Occupational disorder of Ge is also proved to exist in the CDW phase due to the random selection of partially dimerized Ge sites.Our work provides useful insights for understanding the unconventional nature of the CDW in FeGe.
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    Three-dimensional magnetization reconstruction from electron optical phase images with physical constraints

    Boyao LyuShihua ZhaoYibo ZhangWeiwei Wang...
    122-132页
    查看更多>>摘要：The ability to characterize three-dimensional(3D)magnetization distributions in nanoscale magnetic materials and devices is es-sential to fully understand their static and dynamic magnetic properties.Phase contrast techniques in the transmission electron microscope(TEM),such as electron holography and electron ptychography,can be used to record two-dimensional(2D)pro-jections of the in-plane magnetic induction of 3D nanoscale objects.Although the 3D magnetic induction can in principle be reconstructed from one or more tilt series of such 2D projections,conventional tomographic reconstruction algorithms do not re-cover the 3D magnetization within a sample directly.Here,we use simulations to describe the basis of an improved model-based algorithm for the tomographic reconstruction of a 3D magnetization distribution from one or more tilt series of electron optical phase images recorded in the TEM.The algorithm allows a wide range of physical constraints,including a priori information about the sample geometry and magnetic parameters,to be specified.It also makes use of minimization of the micromagnetic energy in the loss function.We demonstrate the reconstruction of the 3D magnetization of a localized magnetic soliton—a hopfion ring—and discuss the influence of noise,choice of magnetic constants,maximum tilt angle and number of tilt axes on the result.The algorithm can in principle be adapted for other magnetic contrast imaging techniques in the TEM,as well as for other magnetic characterization techniques,such as those based on X-rays or neutrons.
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    Al1-xScxSbyN1-y:An opportunity for ferroelectric semiconductor field effect transistor

    Shujin GuoXianghua KongHong Guo
    133-140页
    查看更多>>摘要：For the in-memory computation architecture,a ferroelectric semiconductor field-effect transistor(FeSFET)incorporates ferro-electric material into the FET channel to realize logic and memory in a single device.The emerging group Ⅲ nitride material Al1-xScxN provides an excellent platform to explore FeSFET,as this material has significant electric polarization,ferroelectric switching,and high carrier mobility.However,steps need to be taken to reduce the large band gap of～5 eV of Al1-xScxN to improve its transport property for in-memory logic applications.By state-of-the-art first principles analysis,here we predict that alloying a relatively small amount(less than～5％)of Sb impurities into Al1-xScxN very effectively reduces the band gap while maintaining excellent ferroelectricity.We show that the co-doped Sb and Sc act cooperatively to give a significant band bowing leading to a small band gap of～1.76 eV and a large polarization parameter～0.87 C/m2,in the quaternary Al1-xScxSbyN1-y com-pounds.The Sb impurity states become more continuous as a result of interactions with Sc and can be used for impurity-mediated transport.Based on the Landau-Khalatnikov model,the Landau parameters and the corresponding ferroelectric hysteresis loops are obtained for the quaternary compounds.These findings indicate that Al1-xScxSbyN1-y is an excellent candidate as the channel material of FeSFET.
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    High temperature superconductor Na2B2H stabilized by hydrogen intercalation under ambient pressure

    Wendi ZhaoDefang DuanZhengtao LiuZihao Huo...
    141-148页
    查看更多>>摘要：Hydrogenated metal borides have attracted much attention due to their potential high-temperature superconductivity.Here,we propose a new strategy for hydrogen intercalation tuning the stability and superconductivity of the boron honeycomb sublattice,and predict an unprecedented layered compound Na2B2H,which hosts excellent superconductivity.Strikingly,the super-conducting transition temperature(Tc)of Na2B2H reaches 42 K at ambient pressure.The Tc value can be further increase to 63 K under 5％biaxial tensile strain.The excellent superconductivity originates from the strong electron-phonon coupling between theσ-bonding bands near the Fermi level and the B-B stretching optical E'modes.The interstitial electron localization and crystal orbitals of the H-intercalated Na ion layer well match the boron honeycomb lattice and act as a chemical template to stabilize the B layer.Furthermore,the introduction of hydrogen tuned the Fermi level,and the coupling vibration of Na and H ions effectively enhanced the dynamic stability of the structure.Na2B2H represents a new family of layered high-temperature superconductors,and the strategy of stabilizing the honeycomb boron sublattice via chemical template hosts great potential for application to more layered compounds.
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    Establishing HI mass vs.stellar mass and halo mass scaling relations using an abundance matching method

    Yi LuXiaohu YangChengze LiuHaojie Xu...
    149-163页
    查看更多>>摘要：We combined data from the Sloan Digital Sky Survey(SDSS)and the Arecibo Legacy Fast ALFA Survey(ALFALFA)to es-tablish the HI mass vs.stellar mass and halo mass scaling relations using an abundance matching method that is free of the Malmquist bias.To enable abundance matching,a cross-match between the SDSS DR7 galaxy group sample and the ALFALFA HI sources provides a catalog of 16520 HI-galaxy pairs within 14270 galaxy groups(halos).By applying the observational com-pleteness reductions for both optical and HI observations,we used the remaining 8180 ALFALFA matched sources to construct the model constraints.Taking into account the dependence of HI mass on both the galaxy and group properties,we establish two sets of scaling relations:one with a combination of stellar mass,(g-r)color and halo mass,and the other with stellar mass,specific star-formation rate(sSFR),and halo mass.We demonstrate that our models can reproduce the HI mass component as both stellar mass and halo mass.Additional tests showed that the conditional HI mass distributions as a function of the cosmic web type and the satellite fractions were well recovered.
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    Forecasting supernova observations with the CSST:I.Photometric samples

    Chengqi LiuYouhua XuXianmin MengXin Zhang...
    164-177页
    查看更多>>摘要：The China Space Station Telescope(CSST,also known as Xuntian)is a serviceable two-meter-aperture wide-field telescope op-erating in the same orbit as the China Space Station.The CSST plans to survey a sky area of 17,500 deg2 of the medium-to-high Galactic latitude to a depth of 25-26 AB mag in at least 6 photometric bands over 255-1,000 nm.Within such a large sky area,slitless spectra will also be taken over the same wavelength range as the imaging survey.Even though the CSST survey is not dedicated to time-domain studies,it would still detect a large number of transients,such as supernovae(SNe).In this paper,we simulate photometric SN observations based on a strawman survey plan using the SNCOSMO package.During its 10-year survey,the CSST is expected to observe about 5 million SNe of various types.With quality cuts,we obtain a"gold"sample that com-prises roughly 7,400 SNe Ia,2,200 SNe Ibc,and 6,500 SNe Ⅱ candidates with correctly classified percentages reaching 91％,63％,and 93％(formally defined as classification precision),respectively.The same survey can also trigger alerts for the detection of about 15,500 SNe Ⅰa(precision 61％)and 2,100 SNe Ⅱ(precision 49％)candidates at least two days before the light maxima.Moreover,the near-ultraviolet observations of the CSST will be able to catch hundreds of shock-cooling events serendipitously every year.These results demonstrate that the CSST can make a potentially significant contribution to SN studies.
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    Unveiling the early universe:Axion-like particles and their role in primordial structure formation

    Sergey G.Rubin
    178-179页
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    Cold gas contents of galaxies and their relations to the stellar and dark-matter components

    Houjun Mo
    180页
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