Zigzag Lattice Research Articles

Strain‐Modulated Hydrogen Production Performance in Monolayer MoS2 Electrocatalysis Nanodevices

AbstractThe integration of flexible micro‐ and nanodevices plays a pivotal role in investigating stress‐enhanced performances and underlying intrinsic mechanisms for two‐dimensional materials. This study presents the fabrication of single‐crystal flexible devices using monolayer MoS2 and its catalytic activities for the hydrogen evolution reaction under stress conditions. A metallic conductive layer was deposited on the photoresist surface via magnetron sputtering, overcoming the challenges associated with lithography on insulating substrates using electron beam lithography (EBL). The results demonstrate optimal etch patterns with a metal modification layer thickness of 10.97 nm. Leveraging this flexible device fabrication process, a single‐layer MoS2 single‐nanosheet flexible micro/nano device was developed and subsequently strain‐modulated (stretched along the zigzag lattice direction with the armchair lattice direction as the axis). A significant enhancement is observed in the electrocatalytic hydrogen evolution performance as the strain increases from 0 % to 0.40 %. Notably, the onset overpotential decreased from 155.6 to 95.7 mV, and the Tafel slope decreased from 175.3 to 98.6 mV dec−1. This study provides new insights into the design and performance of strain devices for two‐dimensional (2D) monocrystalline/polycrystalline materials.

Microstructured Organic Cavities with High‐Reflective Flat Reflectors Fabricated by Using a Nanoimprint‐Bonding Process

AbstractThe integration of photonic microstructure into organic microcavities represents an effective strategy for manipulating eigenstates of cavity or polariton modes. However, well‐established fabrication processes for microstructured organic microcavities are still lacking. This study proposes a nanoimprint‐bonding process as a novel fabrication method for microstructured organic microcavities. This process relies on a UV nanoimprint technique utilizing two different photopolymer resins, enabling the independent fabrication of highly reflective reflectors and photonic microstructures without compromising the accuracy of each. The resulting organic microcavities demonstrate spatially localized photonic modes within dot structures and their nonlinear responses on the pumping fluence. Furthermore, a highly precise photonic band is confirmed within a honeycomb lattice structure, which is owing to the high quality factor of the cavity achievable with the nanoimprint‐bonding process. Additionally, a topological edge state is also observable within a zigzag lattice structure. These results highlight the significant potential of the fabrication method for advancing organic‐based photonic devices, including lasers and polariton devices.

Homoclinic breather, periodic wave, lump solution, and M-shaped rational solutions for cold bosonic atoms in a zig-zag optical lattice

Abstract In this article, the equation showing the cold bosonic atoms in a zig-zag optical lattice model for some breathers, M-shaped solution and lump soliton solution, homoclinic breather pulses, breather lump pulses, periodic-cross kink wave, kink cross-rational propagation, and interaction between lump periodic and kink wave was examined. Some M-shaped solution, M-shaped interaction with periodic and kink, M-shaped interaction with rogue and kink, M-shaped rational solution, M-shaped rational solution with one kink, M-shaped rational solution with two kink, solutions for lump soliton waves, lump one kink waves, lump two kink waves, periodic-cross lump wave propagation, periodic wave propagation, rogue wave propagation, and multiwave propagation were also acquired. Likewise, our solution was also graphically presented, and also their stability was checked.

Transition Characteristics of Non‐Hermitian Skin Effects in a Zigzag Lattice Without Chiral Symmetry

AbstractNon‐Hermitian systems recently have attracted tremendous attention due to their plentiful unique and fascinating properties, among which is the localization of an otherwise extensive bulk eigen‐state at the boundary when the open boundary condition (OBC) is imposed, an interesting phenomenon now referred to as non‐Hermitian skin effect (NHSE). Here, a non‐Hermitian Zigzag lattice model with/without chiral symmetry is investigated with respect to different nearest‐neighbor and long‐range hopping amplitudes and study the transition signature of NHSE by extracting information from the complex eigen‐energy spectra of the system under the periodic boundary condition (PBC), which is verified by the directional inverse participation ratio under OBC. Such an approach provides great simplicity in judging transitions of NHSE especially in lattices without chiral symmetry, where the obtained transition signatures are further confirmed by calculating the topological winding number of the energy under PBC. This work reveals a fundamental way to explore transitions of NHSE, and has a potential in helping understand more other complicated topological physics unique to non‐Hermitian systems.

Magnetic solitons due to interfacial chiral interactions

We study solitons in a zig-zag lattice of magnetic dipoles. The lattice comprises two sublattices of parallel chains with magnetic dipoles at their vertices. Due to orthogonal easy planes of rotation for dipoles belonging to different sublattices, the total dipolar energy of this system is separable into a sum of symmetric and chiral long-ranged interactions between the magnets where the last takes the form of Dzyaloshinskii–Moriya (DM) coupling. For a specific range of values of the offset between sublattices, the dipoles realize an equilibrium magnetic state in the lattice plane, consisting of one chain settled in an antiferromagnetic (AF) parallel configuration and the other in a collinear ferromagnetic fashion. If the offset grows beyond this value, the internal DM field stabilizes two Bloch domain walls at the edges of the AF chain. The dynamics of these solitons is studied by deriving the long-wavelength lagrangian density for the easy axis antiferromagnet. We find that the chiral couplings between sublattices give rise to an effective magnetic field that stabilizes the solitons in the antiferromagnet. When the chains displace respect to each other, an emergent Lorentz force accelerates the domain walls along the lattice.

Forecasting the dynamics of the model of cold bosonic atoms in a zig-zag optical lattice by symbolic computation

The work aims to explore the exponential rational function technique and the generalized Kudryashov procedure to investigate one of the most important equations which is the equation of cold bosonic atoms in a zig-zag optical lattice. The considered equation is reduced to a supreme equation by using the continuum approximation which describes the soliton’s dynamics with the implication pulse variables. The adopted techniques are accurate, simple, straightforward, and succinct to compute.

Intrinsic chiral field as vector potential of the magnetic current in the zig-zag lattice of magnetic dipoles

Chiral magnetic insulators manifest novel phases of matter where the sense of rotation of the magnetization is associated with exotic transport phenomena. Effective control of such phases and their dynamical evolution points to the search and study of chiral fields like the Dzyaloshinskii–Moriya interaction. Here we combine experiments, numerics, and theory to study a zig-zag dipolar lattice as a model of an interface between magnetic in-plane layers with a perpendicular magnetization. The zig-zag lattice comprises two parallel sublattices of dipoles with perpendicular easy plane of rotation. The dipolar energy of the system is exactly separable into a sum of symmetric and antisymmetric long-range exchange interactions between dipoles, where the antisymmetric coupling generates a nonlocal Dzyaloshinskii–Moriya field which stabilizes winding textures with the form of chiral solitons. The Dzyaloshinskii–Moriya interaction acts as a vector potential or gauge field of the magnetic current and gives rise to emergent magnetic and electric fields that allow the manifestation of the magnetoelectric effect in the system.

Analysis of propagating wave structures of the cold bosonic atoms in a zig-zag optical lattice via comparison with two different analytical techniques.

The wave propagation has the significant role in the field of coastal engineering and ocean. In the geographical fields, waves are primary source of environmental process owed to energy conveyance on floating structure. This study aims to investigate the system of cold bosonic atoms in zig-zag optics lattices. The solitonic patterns of the considered model successfully surveyed by using two integrated analytical techniques new extended direct algebraic and frac{G'}{G^{2}} expansion method. The exact solutions are presented by rational, trigonometric, hyperbolic and exponential functions. On the basis of solitons, we need to show that which one is more integrated and robust scheme. These solutions will help to understood the dynamics of cold bosonic atoms in zig-zag optical lattices and the several other systems. Three dimensional as well as two dimensional comparison presented for a cold bosonic atoms model solutions which are revealed diagrammatically for appropriate parameters by using Mathematica. This study will help physicists to predict some new hypothesis and theories in the field of mathematical physics.

Dipole-exchange spin waves in two-dimensional van der Waals ferromagnetic films and stripes

A spin-wave (SW) theory that includes the long-range dipole–dipole interactions is presented for monolayers of van der Waals (vdW) ferromagnets for which the magnetic ions lie on a two-dimensional honeycomb lattice. The dipolar interactions provide an additional anisotropy in these materials, along with the Ising exchange interaction and/or single-ion anisotropies that typically stabilize the two-dimensional magnetic ordering. Analytical results for the linearized SW energies are obtained for the ferromagnets in two geometries: complete films and finite-width stripes (or ribbons). In both cases it is found that the inclusion of the dipole–dipole interactions leads to a shift and sometimes a splitting of the magnetic modes in the vdW structure. Also, in the latter case, where the edges are assumed to be along the zigzag lattice directions, the dipole–dipole interactions are found to play a role, as well as the exchange interactions, in modifying the localized edge SWs. Numerical examples are given, including applications to the ferromagnet CrI3.

Multipartite nonlocality and topological quantum phase transitions in a spin-1/2 XXZ model on a zigzag lattice

Multipartite nonlocality and topological quantum phase transitions in a spin-1/2 XXZ model on a zigzag lattice

Dynamical behaviors and abundant optical soliton solutions of the cold bosonic atoms in a zig-zag optical lattice model using two integral schemes

In this present paper, we obtain hyperbolic, exponential, trigonometric function, other soliton solutions, and their combinations for the cold bosonic atoms in a zig-zag optical lattice model based on two efficient methods, such as the generalized Riccati equation mapping (GREM) method and generalized Kudryashov (GK) method. The used techniques are very reliable and effective tools and provide numerous exact soliton solutions of the nonlinear PDE. The zig-zag optical lattice model, widely used to represent the nonlinear wave and the soliton dynamics in fluid dynamics and plasma physics, is examined in this article to obtain exact optical soliton solutions and study their physical properties. For this, we first convert a partial differential equation (PDE) into an ordinary differential equation (ODE) by employing wave transformation and then split the equation into imaginary and real parts. The derived optical soliton solutions are illustrated graphically using Mathematica software to distinguish constant parameter values. Consequently, bell-shape, anti-bell-shape, traveling wave, periodic, mix periodic, singular soliton, and some new types of solitons demonstrate to validate these acquired outcomes with physical phenomena and make the results worthy. Furthermore, the 3D, 2D, and contour graphs are sketched to assign suitable constant parameters to illustrate the physical phenomena of the obtained solutions. The accomplished soliton solutions indicate that the applied computational system is a direct, reliable, productive, and more complex physical phenomenon. Symbolic computation is used in the software package Mathematica to obtain the various soliton solutions and different dynamical behavior of the newly formed solutions

Localization of electromagnetic waves in a zigzag lattice of waveguides with competing cubic and quintic nonlinear responses

The zigzag waveguide array is considered, where even waveguides are composed of optically linear material, and their nearest neighbors are characterized by positive cubic nonlinearity and negative fifth-order nonlinearity. In the continuum (long-wave) approximation the solutions of the system of coupled wave equations are found, which describe waves localized in the lattice and harmonic propagating waves. Keywords: nonlinear waves, discrete photonics, waveguides, solitons.

Optical switching of topological phase in a perovskite polariton lattice.

Strong light-matter interaction enriches topological photonics by dressing light with matter, which provides the possibility to realize active nonlinear topological devices with immunity to defects. Topological exciton polaritons-half-light, half-matter quasiparticles with giant optical nonlinearity-represent a unique platform for active topological photonics. Previous demonstrations of exciton polariton topological insulators demand cryogenic temperatures, and their topological properties are usually fixed. Here, we experimentally demonstrate a room temperature exciton polariton topological insulator in a perovskite zigzag lattice. Polarization serves as a degree of freedom to switch between distinct topological phases, and the topologically nontrivial polariton edge states persist in the presence of onsite energy perturbations, showing strong immunity to disorder. We further demonstrate exciton polariton condensation into the topological edge states under optical pumping. These results provide an ideal platform for realizing active topological polaritonic devices working at ambient conditions, which can find important applications in topological lasers, optical modulation, and switching.

Z2 phases and Majorana spectroscopy in paired Bose-Hubbard chains

We investigate the Bose-Hubbard chain in the presence of nearest-neighbor pairing. The pairing term gives rise to an unusual gapped $\mathbb{Z}_2$ Ising phase that has number fluctuation but no off-diagonal long range order. This phase has a strongly correlated many-body doubly degenerate ground state which is effectively a gap-protected macroscopic qubit. In the strongly interacting limit, the system can be mapped onto an anisotropic transverse spin chain, which in turn can be mapped to the better-known fermionic sister of the paired Bose-Hubbard chain: the Kitaev chain which hosts zero-energy Majorana bound states. While corresponding phases in the fermionic and bosonic systems have starkly different wavefunctions, they share identical energy spectra. We describe a possible cold-atom realization of the paired Bose-Hubbard model in a biased zig-zag optical lattice with reservoir-induced pairing, opening a possible route towards experimental Kitaev chain spectroscopy.

Optical solutions of cold bosonic atoms in a zig-zag optical lattice

In this paper, using the continuum approximation and from a discrete equation governing a system of cold bosonic atoms in zig-zag optical lattices derived an equation in a continuum domain. With two different methods, namely the $$exp_a$$ function method and the Hyperbolic function method, found many solutions of the equation considered. These solutions are Hyperbolic solutions and trigonometric solutions. Discrete representations have been done to observe their behaviors. These results will help to understand the dynamics of cold bosonic atoms in zig-zag optical lattices and several other systems. More importantly, in this article derived the Lagrangian and the stability condition of the model studied. The methods employed here are very simple and concise.

Amorphous NaVOPO 4 as a High-Rate and Ultrastable Cathode Material for Sodium-Ion Batteries

The low cost and profusion of sodium resources make sodium-ion batteries (SIBs) a potential alternative to lithium-ion batteries for grid-scale energy storage applications. However, the use of conv...

Symmetry-protected topological phase transitions and robust chiral order on a tunable zigzag lattice

Symmetry fractionalization, generating a large amount of symmetry-protected topological phases, provides scenarios for continuous phase transitions different from spontaneous symmetry breaking. However, it is hard to detect these symmetry-protected topological phase transitions experimentally. Motivated by the recent development of highly tunable ultracold polar molecules, we show that the setup in a zigzag optical lattice of this system provides a perfect platform to realize symmetry-protected topological phase transitions. By using infinite time-evolving block decimation, we obtain the phase diagram in a large parameter regions and find another scheme to realize the long-sought vector chiral phase, which is robust from quantum fluctuations. We discuss the existence of the chiral phase by an effective field analysis.

Universal Oriented van der Waals Epitaxy of 1D Cyanide Chains on Hexagonal 2D Crystals.

The atomic or molecular assembly on 2D materials through the relatively weak van der Waals interaction is quite different from the conventional heteroepitaxy and may result in unique growth behaviors. Here, it is shown that straight 1D cyanide chains display universal epitaxy on hexagonal 2D materials. A universal oriented assembly of cyanide crystals (AgCN, AuCN, and Cu0.5Au0.5CN) is observed, where the chains are aligned along the three zigzag lattice directions of various 2D hexagonal crystals (graphene, h‐BN, WS2, MoS2, WSe2, MoSe2, and MoTe2). The potential energy landscape of the hexagonal lattice induces this preferred alignment of 1D chains along the zigzag lattice directions, regardless of the lattice parameter and surface elements as demonstrated by first‐principles calculations and parameterized surface potential calculations. Furthermore, the oriented microwires can serve as crystal orientation markers, and stacking‐angle‐controlled vertical 2D heterostructures are successfully fabricated by using them as markers. The oriented van der Waals epitaxy can be generalized to any hexagonal 2D crystals and will serve as a unique growth process to form crystals with orientations along the zigzag directions by epitaxy.

Macroscale single crystal graphene templated directional alignment of liquid-crystal microlens array for light field imaging

Single crystal graphene (SCG) as a transparent conductive electrode material with a relatively strong liquid crystal molecule anchoring energy is expected to provide remarkable improvements to the functionalities of electro-optical devices. Here, we efficiently grew macroscale SCG on Cu(111) and transferred it onto a silica substrate to fabricate a liquid-crystal microlens array (LCMLA) integrated with an arrayed photodetector. As shown, the LC molecules can be aligned along a desired direction over the SCG electrode with the zigzag lattice of the graphene. Furthermore, we demonstrate a prototypical plenoptic camera using the SCG-LCMLA with a controlled unidirectional LC alignment. Dual mode imaging to acquire both two-dimensional and light field images was realized by integrating photodetectors with the electrically adjustable SCG-LCMLA.

On the nonexistence of degenerate phase-shift multibreathers in Klein–Gordon models with interactions beyond nearest neighbors

Abstract In this work, we study the existence of, low amplitude, phase-shift multibreathers for small values of the linear coupling in Klein–Gordon chains with interactions beyond the classical nearest-neighbor (NN) ones. In the proper parameter regimes, the considered lattices bear connections to models beyond one spatial dimension, namely the so-called zigzag lattice, as well as the two-dimensional square lattice or coupled chains. We examine initially the necessary persistence conditions of the system derived by the so-called Effective Hamiltonian Method, in order to seek for unperturbed solutions whose continuation is feasible. Although this approach provides useful insights, in the presence of degeneracy, it does not allow us to determine if they constitute true solutions of our system. In order to overcome this obstacle, we follow a different route. By means of a Lyapunov–Schmidt decomposition, we are able to establish that the bifurcation equation for our models can be considered, in the small energy and small coupling regime, as a perturbation of a corresponding, beyond nearest-neighbor, discrete nonlinear Schrodinger equation. There, nonexistence results of degenerate phase-shift discrete solitons can be demonstrated by an additional Lyapunov–Schmidt decomposition, and translated to our original problem on the Klein–Gordon system. In this way, among other results, we can prove nonexistence of four-site vortex-like waveforms in the zigzag Klein–Gordon model. Finally, briefly considering a one-dimensional model bearing similarities to the square lattice, we conclude that the above strategy is not efficient for the proof of the existence or nonexistence of vortices due to the higher degeneracy of this configuration.