Two-dimensional ferrovalley magnetic materials have attracted much attention due to the applications in valley-based nonvolatile random access memories and valley filters. In this work, using first-principles calculations, we predict a promising class of bipolar magnetic semiconductors, namely non-Janus GdXY(X≠Y=Cl,Br,I) monolayers, which exhibit excellent mechanical and thermal stability, large magnetic moment (8 μB/Gd), and high Curie temperature (above 450 K). When magnetized along the ±z direction, a spontaneous valley polarization can be observed in non-Janus GdXY. Due to the non-zero Berry curvature, the anomalous Hall effect will be able to be observed in non-Janus GdXY. In addition, the system transforms into a semi-semiconductor from a bipolar magnetic semiconductor with increasing biaxial tensile strain. Under the strain of -4%∼+4%, the ferrovalley characteristics can be well maintained. Our findings not only reveal that non-Janus GdXY is a novel room-temperature ferrovalley semiconductor material, but also provide a new platform for designing spintronics and valley electronics devices.
Graphene, a new material with a hexagonal honeycomb sheet structure composed of a single layer of carbon atoms, is the world's thinnest and strongest substance known to human, it has low resistivity and strong light transmission characteristics, so it can be used as a candidate material for integrated circuit chips and new energy batteries. In this paper, we mainly discuss the quantum walk of two non-interacting particles on the graphene structure graph, in which we select coin operator G in coin space HC and construct shift operator S, the time evolution operator U is obtained from the tensor of G and S. Since two particles without interaction can occupy the same site, the initial state is a composite of two particles at the same site. On this foundation, the relation between the relative distance and evolution time of two non-interacting particles is studied by the distance evolution operator.
We study the multiple bright-dark double-pole solitons, multiple negaton-type solitons, and their associated mixed solitons of the coupled space-shifted nonlocal nonlinear Schrödinger equation. These three distinct classes of soliton waveforms are derived from multiple soliton solutions through three different long-wave limit procedures with specific restrictions of the parameters of the solutions. The multiple bright-dark double-pole soliton solutions are symmetric about the point (x02,0), where x0 is the space-shifting parameter of the coupled space-shifted nonlocal nonlinear Schrödinger equation. The space-shifting parameter x0 only affects half of the multiple bright-dark negaton-type solitons, while it has no impact on the other half. The mixed soliton solutions are composed of multiple double-pole solitons and negaton-type solitons. The unique properties of these three distinct classes of soliton waveforms are examined by performing the long-time asymptotic analysis for them.
Phase is a basic ingredient for quantum states since quantum mechanics uses complex numbers to describe quantum states. In this work, we introduce a rigorous framework to quantify the phase of quantum states. To do so, we regard phase as a quantum resource, and specify the free states and free operations. We determine the conditions a phase measure should satisfy and provide some phase measures. We also propose the notion of intrinsic phase for quantum states.
Nonequilibrium flows of a rarefied polyatomic gas through a diverging nozzle under the effect of dynamic pressure are studied. Even in a diverging nozzle, there arises a possibility of occurring choking phenomena if a gas at the inlet of the nozzle is in a nonequilibrium state. And the controllability of gas flows in a nozzle by manipulating the temperature of molecular internal modes such as molecular rotation and vibration is discussed.
We study exotic electronic charge orders and magnetic spin orders in a lattice model which encloses conducting electrons coupled with localized magnetic moments via the exchange-like interaction. By means of numerical simulations based on kernel polynomials method combined with Langevin dynamics, we systematically map out phase diagrams versus exchange coupling strength. At the half-filling case n=1/2 (one electron per lattice site on average), a robust antiferromagnetic insulator is formed at low temperature regime. Away from the half-filling, competition between itinerant electrons and local spin moments drives intertwined charge and spin orders. As a concrete example, at the three-quarter filling n=3/4, we identify various spin orders such as incommensurate stripe order and a long-sought double-Q state. Especially, we demonstrate that such double-Q magnetic order leads to a Dirac semi-metal phase on the square lattice, which is identified by the electronic density of states and optical conductivity. Additionally, we also uncover the spin dynamics of magnetic orders via Landau-Lifshitz method. These findings demonstrate that the interplay between itinerant electrons and preformed local spin moments via the exchange interaction is able to produce complex magnetic orders and electronic charge orders.
The (2+1)-dimensional Sawada-Kotera (SK) equation is an important integrable model, which has wide applications in rivers, lakes, atmosphere, the conformal field and quantum gravity gauge field. In this paper, we introduce a new method for constructing the lump molecules in the SK equation. Then, by using this method and imposing the complexification restrictions, velocity resonant principle, we obtain some hybrid wave solutions, which include the interactions between a lump molecule and two separated solitons, between a lump-lump-soliton molecule and a single soliton, between a lump molecule and a soliton molecule, between a lump molecule and a breather, as well as the lump-lump-breather molecule. Dynamical behaviors of these solutions are analyzed theoretically and graphically. The method introduced can be effectively used to study the wave solutions of other nonlinear PDEs. The results obtained not only enrich the types of soliton molecules, but also can be helpful in the study of the propagation behaviors of nonlinear waves.
We consider the ways in which magnetically hard materials can be used as the working materials in thermomagnetic power generation (TMG) cycles in order to expand the area in the magnetisation vs. applied field (M−H) plane available for energy conversion. There are 3 parts to this Perspective. First, experiments on commercially available hard ferrites reveal that, while these materials are not yet good TMG candidates, hard ferromagnets with higher thermal conductivity and a greater change of magnetization with temperature could outperform existing TMG materials. Second, computational results indicate that biasing a soft magnet with a hard ferromagnet is essentially equivalent to shifting the M−H loop by an amount proportional to the field of the biasing magnet. Work outputs under biased conditions show a substantial improvement over unbiased cycles, but experimental verification is needed. Third, we discuss the rationale for exploring artificial spin reorientation materials as novel TMG working materials.
Macrorealism is a belief that constitutes the core of our perception of reality in the everyday world. The Leggett-Garg (LG) test is a conceptually elegant approach for probing the compatibility between the notion of macrorealism and quantum theory. However, a conclusive LG test hinges on how one fixes the operational invasiveness loophole, i.e., how the statistical form of non-invasive measurability assumption is guaranteed in an LG test. Despite many attempts to close this loophole, no consensus has been achieved yet. In this work, we propose a simple and elegant scheme based on indefinite causal order in quantum switch experiment, which enables us to close this loophole, and eventually, the LG test becomes a conclusive test of macrorealism.
According to the analysis of the lubrication theory, the surface wave will develop in the region of low Reynolds number, and the presence of an odd viscosity. Fourth order nonlinear wave equations (generalized Kuramoto-Sivashinsky equation) that appear in the theory of thin liquid films are introduced. Analyses of linear stability for sinusoidal waves in various regimes are investigated. The Hopf bifurcation points for the traveling waves are investigated. Surface wave stability will arise more quickly if an odd viscosity is present.
A singularity induced bifurcation (SIB) phenomenon is used in this paper to analyze transonic flow in an unsteady gravitational field. Multiple sonic crossings by a single trajectory in the gravitational field are characterized by the divergence of eigenvalues of the linearized model, folded saddles and nodes, as well as the existence of impasse points at the sonic manifold. The analysis is done in the framework of self-similarity shockless solutions. Two particular implicit ODE models of the transonic flows in the gravitational field around a central point mass are analyzed.
This research is carried out to characterize the mechanical behavior of boron nitride nanocones (BNNCs) via molecular dynamics (MD) simulations using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The calculations of atomic interactions are performed based on the Tersoff-type potential function. The five elastic moduli are determined by applying four mechanical loadings i. e. uniaxial stretching, axial twist, plane-strain biaxial tension, and in-plane shear. It is found that all elastic constants depend on the apex angle of BNNCs, whereas wider ones have lower Young's and longitudinal shear moduli. In contrast, as the apex angle of the nanocones increases, their plane-strain bulk moduli and in-plane shear constants increase. In addition, Poisson's ratio decreases with an increase in the apex angle and length of the BNNCs. Moreover, the shorter and sharper BNNCs, the higher values of strain at which they fail under uniaxial tensile and axial twist loadings.
Complex systems constitute a cross-disciplinary field that studies natural and societal phenomena. In general, complexity relates to different aspects of a system, such as emergent behaviours, interaction patterns, and other properties. Also, complexity can refer to the resources required to accomplish a task. Here, we review a limited collection of methods for studying complexity across different topics. The resulting picture highlights interesting relationships between complexity and distance, showing up in all considered systems, from phase transitions to black hole evolution. We conclude by discussing related implications and a few examples beyond Physics that corroborate the validity of the highlighted relationships.
A thermochemical model in the parametric zone of hysteresis with coexisting equilibrium and oscillatory attractors is considered. For the stochastic version of the model, we study probabilistic mechanisms of multi-stage noise-induced transformations of oscillatory modes. These transformations are associated with stochastic P-bifurcations. Constructive abilities of the analytical method based on confidence domains are demonstrated. It is discussed which of the coexisting regimes under increasing noise is more dangerous in the context of temperature blow-ups.
A new method for studying the internal structure of micro-objects using synchrotron radiation based on the use of a planar nanofocusing compound refractive lens is proposed. The method registers the integral intensity of radiation after passing through the object. In this case, locality is ensured by focusing the beam into a line of nanometer width. Phase contrast is not used. The profile of object thickness inside the x-ray beam is obtained immediately. However, the two-dimensional structure of the object image is calculated using the specific tomography method. The method does not require complex mathematical calculations and gives a result with a very high accuracy. An experiment was simulated with a silicon carbide substrate for typical values of all parameters to illustrate the operation of the method.
In this work, we study the effect of mismatch strain for coherent interface between the core and the shell of a Type I core/shell quantum dot (QD) on the ground-state energy of a particle in the core/shell QD under the framework of linear elasticity. Closed-form solution of the energy of the particle at ground state for the core and the shell being cubic structure is obtained, and the first order solution of the energy of the particle at ground state for the core and the shell being wurtzite structure is derived. The numerical results show that the energy change at ground state is proportional to hydrostatic stress and nonlinearly increases with the increase of the ratio of the shell thickness to the core radius.
