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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）

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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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    An improved bound on accelerated light dark matter

    Liangliang SuLei WuBin Zhu
    105-118页
    查看更多>>摘要：Light(sub-GeV)dark matter has gained increasing interest in terms of direct detection.Accelerated dark matter is a promising candidate that can generate detectable nuclear recoil energy within the sub-GeV range.Because of the large kinetic energy,its interactions with the nucleus are predominantly governed by inelastic scattering,including quasi-elastic and deep inelastic scat-tering.In this work,we calculated the inelastic effects in dark matter-Earth scattering mediated by a vector particle.Our analysis revealed that the impact of inelastic scattering relies on the mediator mass and the kinetic energy spectrum of dark matter.The results exhibited considerable disparity:the upper bounds of the exclusion limit for the spin-independent cross-section between accelerated dark matter and nuclei via a heavy mediator differ by several tens of times when inelastic scattering is considered.
      原文链接:
    • 万方数据
    • 维普

    Single-step-etched ultra-compact metamaterial grating coupler enabled by a hierarchical inverse design approach

    Qiao WangRuiqi LuoNan LiuMaojing Hou...
    119-126页
    查看更多>>摘要：With the concept of metamaterials introduced into integrated photonics,subwavelength structures have gained popularity for their ability to create devices with ultra-compact size,high performance,and versatile functionalities.However,traditional metamaterial design methods are usually based on empirical templates and physical approximations,lacking the ability to design free-form metamaterial structures and optimize entire devices globally.In this work,we propose a hierarchical inverse design approach that combines a conventional effective refractive index based metamaterial structures design with a follow-up global topology optimization.The empirical metamaterial grating coupler design based on effective refractive index engineering faces inaccurate index extraction and insufficient approximation of wavevector matching conditions,which deteriorates coupling efficiency,especially for fully-etched devices with the decreased tapering region.Fortunately,a subsequent overall topology optimization step can well compensate for the negative effect of the shrinking device footprint to increase the efficiency of the metamaterial grating coupler.We demonstrate a 23 μm× 10 μm ultra-compact metamaterial grating coupler with single-step-etched to couple light between a fiber and a 500 nm single-mode silicon waveguide in the O-band.Experimental measurement shows an insertion loss of 3.17 dB and a 3 dB bandwidth of 77 nm,making it the smallest footprint device ever reported.
      原文链接:
    • 万方数据
    • 维普

    The higher-order topological pumping explored in the 2D acoustic crystal

    Yanqiu WangBin LiangJianchun Cheng
    127-133页
    查看更多>>摘要：The topological pumping has been instrumental in advancing our understanding of topological phase transitions in various physical systems,which can be extended to uncover intriguing higher-order topological phases in the lower-dimensional system.Here,we propose a theoretical exploration of topological dipole pumping on an acoustic square superlattice by cyclically modulating intracell couplings,which shares the topological nature of an extended three-dimensional system with chiral hinge states.Using the multipole chiral numbers,we characterize the higher-order topological phases that arise during the evolution.The evolution of topological phase transitions is verified by numerical simulations and shows corner states are transferred across the bulk.Our findings can inspire the construction of chiral hinge states in artificial crystals,opening up new possibilities for the design of devices allowing the unidirectional propagation of sound.
      原文链接:
    • 万方数据
    • 维普

    Theoretical study on magnetocaloric effect and its electric-field regulation in CrI3/metal heterostructure

    Weiwei HeZiming TangQihua GongMin Yi...
    134-141页
    查看更多>>摘要：The extraordinary properties of a heterostructure by stacking atom-thick van der Waals(vdW)magnets have been extensively studied.However,the magnetocaloric effect(MCE)of heterostructures that are based on monolayer magnets remains to be ex-plored.Herein,we deliberate MCE of vdW heterostructure composed of a monolayer CrI3 and metal atomic layers(Ag,Hf,Au,and Pb).It is revealed that heterostructure engineering by introducing metal substrate can improve MCE of CrI3,particularly boosting relative cooling power to 471.72 μJ m-2 and adiabatic temperature change to 2.1 K at 5 T for CrI3/Hf.This improved MCE is ascribed to the enhancement of magnetic moment and intralayer exchange coupling in CrI3 due to the CrI3/metal het-erointerface induced charge transfer.Electric field is further found to tune MCE of CrI3 in heterostructures and could shift the peak temperature by around 10 K in CrI3/Hf,thus manipulating the working temperature window of MCE.These theoretical results could enrich the research on low-dimensional magnetocaloric materials.
      原文链接:
    • 万方数据

    Uncovering the magnetic response of open-shell graphene nanostructures on metallic surfaces at different doping levels

    Zengfu OuJun WangJihai ZhangYukang Ding...
    142-148页
    查看更多>>摘要：Open-shell graphene nanostructures(GNs)are promising candidates for future spintronics and quantum technologies.Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surfaces.Meanwhile,the doping effect of metallic surfaces is inevitably present and can significantly tune their electronic and magnetic properties.Here,we investigate the zigzag end states of open-shell 7-armchair graphene nanoribbons(7-AGNRs)on Au(111),Au(100)and Ag(111)surfaces.Combined with the manipulation of a scanning tunneling microscope,we demonstrate that the end states can be tuned from empty states to singly occupied states and to doubly occupied states by substrate doping.Furthermore,the singly occupied states can be finely tuned,with the occupancy number of the states and related magnetic behaviors uncovered by experiments at different temperatures and magnetic fields.Our results provide a comprehensive study of the magnetic response of open-shell GNs on metallic surfaces at different doping levels.
      原文链接:
    • 万方数据
    • 维普

    Facile intercalation of alkali ions in WO3 for modulated electronic and optical properties:Implications for artificial synapses and chromogenic application

    Changmeng HuanZihan LuSilin TangYongqing Cai...
    149-160页
    查看更多>>摘要：Tungsten oxides(WO3)are widely recognized as multifunctional systems owing to the existence of rich polymorphs.These diverse phases exhibit distinct octahedra-tilting patterns,generating substantial tunnels that are ideally suited for iontronics.However,a quantitative comprehension regarding the impact of distinct phases on the kinetics of intercalated conducting ions remains lacking.Herein,we employ first-principles calculations to explore the spatial and orientational correlations of ion transport in γ-and h-WO3,shedding light on the relationship between diffusion barriers and the size of the conducting ions.Our findings reveal that different types and concentrations of alkali-metals induce distinct and continuous lattice distortions in WO3 polymorphs.Specifically,γ-WO3 is more appropriate to accommodate Li+ions,exhibiting a diffusion barrier and coeficient of 0.25 eV and 9.31 × 10-8 cm2 s-1,respectively.Conversely,h-WO3 features unidirectional and sizeable tunnels that facilitate the transport of K+ions with an even lower barrier and a high coeffiicient of 0.11 eV and 2.12×10-5 cm2 s-1,respectively.Fur-thermore,the introduction of alkali-metal into WO3 tunnels tends to introduce n-type conductivity by contributing s-electrons to the unoccupied W 5d states,resulting in enhanced conductivity and tunable electronic structures.These alkali metals in WO3 tunnels are prone to charge transfer,forming small polaronic states and modulating the light absorption in the visible and near-infrared regions.These tunable electronic and optical properties,combined with the high diffusion coefficient,underscore the potential of WO3 in applications such as artificial synapses and chromogenic devices.
      原文链接:
    • 万方数据

    Pressure-induced color change arising from transformation between intra-and inter-band transitions in LuH2±xNy

    Zhe LiuYingjie ZhangShenyang HuangXue Ming...
    161-166页
    查看更多>>摘要：The pressure-induced color change in the nitrogen-doped lutetium hydride has triggered extensive discussions about the underly-ing physics and potential applications.Here,we study the optical response of LuH2±xNy in a broad frequency range at ambient pressure and its evolution with pressure in the visible spectral range.The broad-band optical spectra at ambient pressure re-veal a Drude component associated with intra-band electronic transitions and two Lorentz components(L1 and L2)arising from inter-band electronic transitions.The application of pressure causes a spectral weight transfer from L1 to the Drude component,leading to a blue shift of the plasma edge in the reflectivity spectrum alongside a reduction of the high-frequency reflectivity.Our results suggest that the pressure-induced color change in LuH2±xNy is closely related to the transformation between intra-and inter-band electronic transitions,providing new insights into the mechanism of the pressure-induced color change in LuH2±xNy.
      原文链接:
    • 万方数据

    Theoretical understanding of correlation between magnetic phase transition and the superconducting dome in high-Tc cuprates

    Chen ZhangCai-Xin ZhangSu-Huai WeiHaiqing Lin...
    167-173页
    查看更多>>摘要：Many issues concerning the origin of high-temperature superconductivity(HTS)are still under debate.For example,how the magnetic order varies with doping and its relationship with the superconducting temperature(Tc);and why Tc always peaks near the quantum critical point.In this paper,taking hole-doped La2CuO4 as a classical example,we employ the first-principles band structure and total energy calculations with Monte Carlo simulations to explore how the symmetry-breaking magnetic ground state evolves with hole doping and the origin of a dome-shaped superconductivity region in the phase diagram.We demonstrate that the local antiferromagnetic order and doping play key roles in determining the electron-phonon coupling,thus Tc.Initially,the La2CuO4 possesses a checkerboard local antiferromagnetic ground state.As the hole doping increases,Tc increases with the enhanced electron-phonon coupling strength.But as the doping increases further,the strength of the antiferromagnetic inter-action weakens and spin fluctuation increases.At the critical doping level,a magnetic phase transition occurs that reduces the local antiferromagnetism-assisted electron-phonon coupling,thus diminishing the Tc.The superconductivity disappears in the heavily overdoped region when the ferromagnetic order dominates.These observations could account for why cuprates have a dome-shaped superconductivity region in the phase diagram.Our study,thus,contributes to a fundamental understanding of the correlation between doping,local magnetic order,and superconductivity of HTS.
      原文链接:
    • 万方数据
    • 维普

    Discovery of strong bulk Dzyaloshinskii-Moriya interaction in composition-uniform centrosymmetric magnetic single layers

    Lijun ZhuDavid LujanXiaoqin Li
    174-180页
    查看更多>>摘要：Dzyaloshinskii-Moriya interaction(DMI)is the key ingredient of chiral spintronic phenomena and the emerging technologies based on such phenomena.A nonzero DMI usually occurs at magnetic interfaces or within non-centrosymmetric single crystals.Here,we report the observation of a strong unexpected DMI within a centrosymmetric polycrystalline ferromagnet that has neither a crystal inversion symmetry breaking nor a composition gradient.This DMI is a bulk effect,increases with the thickness of the magnetic layer,and is insensitive to the symmetry of the interfaces or the neighboring materials.We observe a total DMI strength that is a factor of＞2 greater than the highest interfacial DMI in the literature.This DMI most likely arises from the strong spin-orbit coupling,strong orbital hybrization,and a"hidden"long-range asymmetry in the material.Our discovery of the strong unconventional bulk DMI in centrosymmetric,composition-uniform magnetic single layers provides fundamental building blocks for the emerging field of spintronics and will stimulate the exploitation of unconventional spin-orbit phenomena in a wide range of materials.
      原文链接:
    • 万方数据
    • 维普

    Black holes as the source of dark energy:A stringent test with high-redshift JWST AGNs

    Lei LeiLei ZuGuan-Wen YuanZhao-Qiang Shen...
    181-188页
    查看更多>>摘要：Studies have proposed that there is evidence for cosmological coupling of black holes(BHs)with an index of k ≈ 3;hence,BHs serve as the astrophysical source of dark energy.However,the data sample is limited for the redshifts of ≤ 2.5.In recent years,the James Webb Space Telescope(JWST)has detected many high-redshift active galactic nuclei(AGNs)and quasars.Among the JWST NIRSpec-/NIRCam-resolved AGNs,three are determined to be in early-type host galaxies with a redshift of z～4.5-7.However,their M★ and MBH are in tension with the predicted cosmological coupling of black holes with k=3 at a confidence level of～2σ,which challenges the hypothesis that BHs serve as the origin of dark energy.Future work on high-redshift AGNs using the JWST will further assess such a hypothesis by identifying more early-type host galaxies in the higher mass range.
      原文链接:
    • 万方数据
    • 维普