查看更多>>摘要：Moiré superlattices(MSLs)are modulated structures produced from homogeneous or heterogeneous two-dimensional layers stacked with a twist angle and/or lattice mismatch.Enriching the methods for fabricating MSL and realizing the unique emergent properties are key challenges in its investigation.Here we recommend that the spiral dislocation driven growth is another optional method for the preparation of high quality MSL samples.The spiral structure stabilizes the constant out-of-plane lattice distance,causing the variations in electronic and optical properties.Taking SnS2 MSL as an example,we find prominent properties including large band gap reduction(～0.4 eV)and enhanced optical activity.First-principles calculations reveal that these unusual properties can be ascribed to the locally enhanced interlayer interaction associated with the Moiré potential modulation.We believe that the spiral dislocation driven growth would be a powerful method to expand the MSL family and broaden their scope of application.
查看更多>>摘要：In iron-based superconductor Fe(Se,Te),a flat band-like feature near the Fermi level was observed around the Brillouin zone center in the superconducting state.It is under debate whether this is the evidence on the presence of the BCS-BEC[Bardeen-Cooper-Schrieffer(BCS),Bose-Einstein condensation(BEC)]crossover in the superconductor.High-resolution laser-based angle-resolved photoemission measurements are carried out on high quality single crystals of FeSe0.45Te0.55 superconductor to address the issue.By employing different polarization geometries,we have resolved and isolated the dyz band and the topological surface band,making it possible to study their superconducting behaviors separately.The dyz band alone does not form a flat band-like feature in the superconducting state and the measured dispersion can be well described by the BCS picture.We find that the flat band-like feature is formed from the combination of the dyz band and the topological surface state band in the superconducting state.These results reveal the origin of the flat band-like feature and rule out the presence of BCS-BEC crossover in Fe(Se,Te)superconductor.
查看更多>>摘要：The self-intercalation of Cr into pristine two-dimensional(2D)van der Waals ferromagnetic CrTe2,which forms chromium tellurides(CrxTe2),has garnered interest due to their remarkable magnetic characteristics and the wide variety of chemical compositions available.Here,comprehensive basic characterization and magnetic studies are conducted on quasi-2D ferromagnetic Cr1.04Te2 crystals.Measurements of the isothermal magnetization curves are conducted around the critical temperature to systematically investigate the critical behavior.Specifically,the critical exponents β=0.2399,y=0.859,and δ=4.3498,as well as the Curie temperature TC=249.56 K,are determined using various methods,including the modified Arrott plots,the Kouvel-Fisher method,the Widom scaling method,and the critical isotherm analysis.These results indicate that the tricritical mean-field model accurately represents the critical behavior of Cr1.04Te2.A magnetic phase diagram with tricritical phenomenon is thus constructed.Further investigations confirm that the critical exponents obtained conform to the scalar equation near TC,indicating their self-consistency and reliability.Our work sheds light on the magnetic properties of quasi-2D Cr1.04Te2,broadening the scope of the van der Waals crystals for developments of future spintronic devices operable at room temperature.
查看更多>>摘要：In classical matter systems,typical phase-transition phenomena usually stem from changes in state variables,such as temperature and pressure,induced by external regulations such as heat transfer and volume adjustment.However,in active matter systems,the self-propulsion nature of active particles endows the systems with the ability to induce unique collective-state transitions by spontaneously regulating individual properties to alter the overall states.Based on an innovative robot-swarm experimental system,we demonstrate a field-driven active matter model capable of modulating individual motion behaviors through interaction with a recoverable environmental resource field by the resource perception and consumption.In the simulated model,by gradually reducing the individual resource-conversion coefficient over time,this robotic active matter can spontaneously decrease the overall level of motion,thereby actively achieving a regulation behavior like the cooling-down control.Through simulation calculations,we discover that the spatial structures of this robotic active matter convert from disorder to order during this process,with the resulting ordered structures exhibiting a high self-adaptability on the geometry of the environmental boundaries.
查看更多>>摘要：In the current information society,the dissemination mechanisms and evolution laws of individual or collective opin-ions and their behaviors are the research hot topics in the field of opinion dynamics.First,in this paper,a two-layer network consisting of an individual-opinion layer and a collective-opinion layer is constructed,and a dissemination model of opinions incorporating higher-order interactions(i.e.OIHOI dissemination model)is proposed.Furthermore,the dy-namic equations of opinion dissemination for both individuals and groups are presented.Using Lyapunov's first method,two equilibrium points,including the negative consensus point and positive consensus point,and the dynamic equations obtained for opinion dissemination,are analyzed theoretically.In addition,for individual opinions and collective opinions,some conditions for reaching negative consensus and positive consensus as well as the theoretical expression for the dis-semination threshold are put forward.Numerical simulations are carried to verify the feasibility and effectiveness of the proposed theoretical results,as well as the influence of the intra-structure,inter-connections,and higher-order interactions on the dissemination and evolution of individual opinions.The main results are as follows.(i)When the intra-structure of the collective-opinion layer meets certain characteristics,then a negative or positive consensus is easier to reach for individ-uals.(ii)Both negative consensus and positive consensus perform best in mixed type of inter-connections in the two-layer network.(iii)Higher-order interactions can quickly eliminate differences in individual opinions,thereby enabling individ-uals to reach consensus faster.
查看更多>>摘要：Under investigation is an integrable generalization of the Fokas-Lenells equation,which can be derived from the neg-ative power flow of a 2 × 2 matrix spectral problem with three potentials.Based on the gauge transformation of the matrix spectral problem,one kind of Darboux transformation with multi-parameters for the three-component coupled Fokas-Lenells system is constructed.As a reduction,the N-fold Darboux transformation for the generalized Fokas-Lenells equa-tion is obtained,from which the N-soliton solution in a compact Vandermonde-like determinant form is given.Particularly,the explicit one-and two-soliton solutions are presented and their dynamical behaviors are shown graphically.
查看更多>>摘要：This paper addresses the issue of nonfragile state estimation for memristive recurrent neural networks with propor-tional delay and sensor saturations.In practical engineering,numerous unnecessary signals are transmitted to the estimator through the networks,which increases the burden of communication bandwidth.A dynamic event-triggered mechanism,instead of a static event-triggered mechanism,is employed to select useful data.By constructing a meaningful Lyapunov-Krasovskii functional,a delay-dependent criterion is derived in terms of linear matrix inequalities for ensuring the global asymptotic stability of the augmented system.In the end,two numerical simulations are employed to illustrate the feasibil-ity and validity of the proposed theoretical results.
查看更多>>摘要：This paper examines the bipartite consensus problems for the nonlinear multi-agent systems in Lurie dynamics form with cooperative and competitive communication between different agents.Based on the contraction theory,some new con-ditions for the nonlinear Lurie multi-agent systems reaching bipartite leaderless consensus and bipartite tracking consensus are presented.Compared with the traditional methods,this approach degrades the dimensions of the conditions,eliminates some restrictions of the system matrix,and extends the range of the nonlinear function.Finally,two numerical examples are provided to illustrate the efficiency of our results.
查看更多>>摘要：Nonlinear energy sink is a passive energy absorption device that surpasses linear dampers,and has gained significant attention in various fields of vibration suppression.This is owing to its capacity to offer high vibration attenuation and robustness across a wide frequency spectrum.Energy harvester is a device employed to convert kinetic energy into usable electric energy.In this paper,we propose an electromagnetic energy harvester enhanced viscoelastic nonlinear energy sink(VNES)to achieve passive vibration suppression and energy harvesting simultaneously.A critical departure from prior studies is the investigation of the stochastic P-bifurcation of the electromechanically coupled VNES system under narrow-band random excitation.Initially,approximate analytical solutions are derived using a combination of a multiple-scale method and a perturbation approach.The substantial agreement between theoretical analysis solutions and numerical solu-tions obtained from Monte Carlo simulation underscores the method's high degree of validity.Furthermore,the effects of system parameters on system responses are carefully examined.Additionally,we demonstrate that stochastic P-bifurcation can be induced by system parameters,which is further verified by the steady-state density functions of displacement.Lastly,we analyze the impacts of various parameters on the mean square current and the mean output power,which are crucial for selecting suitable parameters to enhance the energy harvesting performance.
查看更多>>摘要：We construct a dual-layer coupled complex network of communities and residents to represent the interconnected risk transmission network between communities and the disease transmission network among residents.It characterizes the process of infectious disease transmission among residents between communities through the SE2IHR model considering two types of infectors.By depicting a more fine-grained social structure and combining further simulation experiments,the study validates the crucial role of various prevention and control measures implemented by communities as primary execu-tors in controlling the epidemic.Research shows that the geographical boundaries of communities and the social interaction patterns of residents have a significant impact on the spread of the epidemic,where early detection,isolation and treatment strategies at community level are essential for controlling the spread of the epidemic.In addition,the study explores the collaborative governance model and institutional advantages of communities and residents in epidemic prevention and control.
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