查看更多>>摘要：The 1T-TiSe2 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-TiSe2 a promising candidate for realizing excitonic condensation.Here,we studied the band gap in lT-TiSe2 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 direction.We found that the conduction and valance bands split into multiple sub-bands in the CDW state due to band folding.As 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 state.More intriguingly,such band gap can be further reduced by the rubidium deposition.The band structure becomes semimetallic in the rubidium-doped sample.Meanwhile,exotic gapless behaviors were observed at the p-d band crossing.Our result characterized the band gap of lT-TiSe2 in three-dimensional Brillouin zone with unpreceded precision.It also suggests a closing of band gap or a potential band inversion in 1T-TiSe2 driven by rubidium deposition.
查看更多>>摘要：It is well known that femtosecond laser pulses can easily spontaneously induce deep-subwavelength periodic surface structures on transparent dielectrics but not on non-transparent semiconductors.Nevertheless,in this study,we demonstrate that using high-numerical-aperture 800 nm femtosecond laser direct writing with controlled pulse energy and scanning speed in the near-damage-threshold regime,polarization-dependent deep-subwavelength single grooves with linewidths of～180 nm can be controllably prepared on Si.Generally,the single-groove linewidth increases slightly with increase in the pulse energy and decrease in the scanning speed,whereas the single-groove depth significantly increases from～300 nm to～600 nm with decrease in the scanning speed,or even to over 1 μm with multi-processing,indicating the characteristics of transverse clamping and longitudinal growth of such deep-subwavelength single grooves.Energy dispersive spectroscopy composition analysis of the near-groove region confirms that single-groove formation tends to be an ultrafast,non-thermal ablation process,and the oxidized deposits near the grooves are easy to clean up.Furthermore,the results,showing both the strong dependence of groove orientation on laser polarization and the occurrence of double-groove structures due to the interference of pre-formed orthogonal grooves,indicate that the extraordinary field enhancement of strong polariza-tion sensitivity in the deep-subwavelength groove plays an important role in single-groove growth with high stability and collimation.
查看更多>>摘要：Silicon(Si)is a competitive anode material owing to its high theoretical capacity and low electrochemical potential.Recently,the prospect of Si anodes in solid-state batteries(SSBs)has been proposed due to less solid electrolyte interphase(SEI)formation and particle pulverization.However,major challenges arise for Si anodes in SSBs at elevated temperatures.In this work,the failure mechanisms of Si-Li6PS5Cl(LPSC)composite anodes above 80 ℃ are thoroughly investigated from the perspectives of interface stability and(electro)chemo-mechanical effect.The chemistry and growth kinetics of LixSi|LPSC interphase are demonstrated by combining electrochemical,chemical and computational characterizations.Si and/or Si-P compound formed at LixSi|LPSC interface prove to be detrimental to interface stability at high temperatures.On the other hand,excessive volume expansion and local stress caused by Si lithiation at high temperatures damage the mechanical structure of Si-LPSC composite anodes.This work elucidates the behavior and failure mechanisms of Si-based anodes in SSBs at high temperatures and provides insights into upgrading Si-based anodes for application in SSBs.
查看更多>>摘要：In Na-ion batteries,O3-type layered oxide cathode materials encounter challenges such as particle cracking,oxy-gen loss,electrolyte side reactions,and multi-phase transitions during the charge/discharge process.This study focuses on surface coating with NiTiO3 achieved via secondary heat treatment using a coating precursor and the surface material.Through in-situ x-ray diffraction(XRD)and differential electrochemical mass spectrometry(DEMS),along with crystal structure characterizations of post-cycling materials,it was determined that the NiTiO3 coating layer facilitates the forma-tion of a stable lattice structure,effectively inhibiting lattice oxygen loss and reducing side reaction with the electrolyte.This enhancement in cycling stability was evidenced by a capacity retention of approximately 74％over 300 cycles at 1 C,marking a significant 30％improvement over the initial sample.Furthermore,notable advancements in rate performance were observed.Experimental results indicate that a stable and robust surface structure substantially enhances the overall stability of the bulk phase,presenting a novel approach for designing layered oxide cathodes with higher energy density.
查看更多>>摘要：The self-powered tissue engineering scaffold with good biocompatibility is of great significance for stimulating nerve cell growth.In this study,silk fibroin(SF)-based fibers with regulatable structure and piezoelectric performance are fabri-cated by dry-spinning and post-treatment.The concentration of SF and calcium ion in spinning dope and the post-treatment affect the conformation transition and crystallinity of SF.As a result,the SF fibers exhibit high piezoelectric coefficient d33(3.24 pm/V)and output voltage(～27 V).Furthermore,these piezoelectric fibers promote the growth of PC-12 cells,demonstrating the promising potential for nerve repair and other energy harvester.
查看更多>>摘要：This paper aims to investigate the multi-soliton solutions of the coupled Lakshmanan-Porsezian-Daniel equations with variable coefficients under nonzero boundary conditions.These equations are utilized to model the phenomenon of nonlinear waves propagating simultaneously in non-uniform optical fibers.By analyzing the Lax pair and the Riemann-Hilbert problem,we aim to provide a comprehensive understanding of the dynamics and interactions of solitons of this system.Furthermore,we study the impacts of group velocity dispersion or the fourth-order dispersion on soliton behav-iors.Through appropriate parameter selections,we observe various nonlinear phenomena,including the disappearance of solitons after interaction and their transformation into breather-like solitons,as well as the propagation of breathers with variable periodicity and interactions between solitons with variable periodicities.
查看更多>>摘要：We investigate the topological properties of a two-chain quantum ladder with uneven legs,i.e.,the two chains differ in their periods by a factor of 2.Such an uneven ladder presents rich band structures classified by the closure of either direct or indirect bandgaps.It also provides opportunities to explore fundamental concepts concerning band topology and edge modes,including the difference of intracellular and intercellular Zak phases,and the role of the inversion symmetry(IS).We calculate the Zak phases of the two kinds and find excellent agreement with the dipole moment and extra charge accumulation.We also find that configurations with IS feature a pair of degenerate two-side edge modes emerging as the closure of the direct bandgap,while configurations without IS feature one-side edge modes emerging as not only the closure of both direct and indirect bandgaps but also within the band continuum.Furthermore,by projecting to the two sublattices,we find that the effective Bloch Hamiltonian corresponds to that of a generalized Su-Schrieffer-Heeger model or the Rice-Mele model whose hopping amplitudes depend on the quasimomentum.In this way,the topological phases can be efficiently extracted through winding numbers.We propose that uneven ladders can be realized by spin-dependent optical lattices and their rich topological characteristics can be examined by near future experiments.
查看更多>>摘要：We explore the gapped graphene structure in the two-dimensional plane in the presence of the Rosen-Morse potential and an external uniform magnetic field.In order to describe the corresponding structure,we consider the propagation of electrons in graphene as relativistic fermion quasi-particles,and analyze it by the wave functions of two-component spinors with pseudo-spin symmetry using the Dirac equation.Next,to solve and analyze the Dirac equation,we obtain the eigenvalues and eigenvectors using the Legendre differential equation.After that,we obtain the bounded states of energy depending on the coefficients of Rosen-Morse and magnetic potentials in terms of quantum numbers of principal n and spin-orbit k.Then,the values of the energy spectrum for the ground state and the first excited state are calculated,and the wave functions and the corresponding probabilities are plotted in terms of coordinates r.In what follows,we explore the band structure of gapped graphene by the modified dispersion relation and write it in terms of the two-dimensional wave vectors Kx and Ky.Finally,the energy bands are plotted in terms of the wave vectors Kx and Ky with and without the magnetic term.
查看更多>>摘要：We study the construction of mutually unbiased bases in Hilbert space for composite dimensions d which are not prime powers.We explore the results for composite dimensions which are true for prime power dimensions.We then provide a method for selecting mutually unbiased vectors from the eigenvectors of generalized Pauli matrices to construct mutually unbiased bases.In particular,we present four mutually unbiased bases in C15.
查看更多>>摘要：We present a quantitative measurement of the horizontal component of the microwave magnetic field of a coplanar waveguide using a quantum diamond probe in fiber format.The measurement results are compared in detail with simulation,showing a good consistence.Further simulation shows fiber diamond probe brings negligible disturbance to the field under measurement compared to bulk diamond.This method will find important applications ranging from electromagnetic compatibility test and failure analysis of high frequency and high complexity integrated circuits.
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