Plane Wave Research Articles

Scattering of a spinning dielectric sphere to polarized plane waves

The exact expression of the wave vector inside a spinning homogeneous dielectric sphere illuminated by polarized plane waves is derived utilizing the “instantaneous rest-frame” hypothesis and Minkowski’s theory. On this basis, the analytical expressions of the electromagnetic field in the rotation sphere system are attained. The asymmetry of the system is discussed, in which the cause is emphasized. The influence of the polarization states and rotation angular velocity on the scattering are analyzed, including the optical rotation effect and photonic hook (PH). The results of this manuscript have extensive application prospects in optical tweezers, particle manipulation, and antenna design.

Reordering of point-vortex lattices under anisotropic diffraction: far-field analysis

Abstract A study of the far-field complex amplitude obtained from initially ordered arrays of N × M point-vortices with equal unitary topological charge embedded in carrier beams with different geometry is presented. This can be understood as the final stationary configuration after the dynamical evolution of the vortices upon propagation, and our aim is to investigate the impact of a geometric anisotropy on the diffraction process by using an elliptic Gaussian beam as a carrier and a rectangular vortex lattice. For comparison, illumination by a circular Gaussian beam and a plane wave diffracted by a rectangular aperture are also analyzed. We show that vortices tend to cluster in some regions under high eccentricity of the carrier and there can be an entire redistribution of the vortices depending on the size of the initial array with respect to the size of the carrier, which inherits some geometric characteristics of the latter.

DFT study of structural, electronic, magnetic, elastic, and thermoelectric properties of Ta-based half-Heusler alloys CsTaX (X = C, Si, and Ge) for spintronics and thermoelectric technologies

The structural, electronic, elastic, magnetic, and thermoelectric characteristics of three novel Ta-based half-Heusler alloys, CsTaC, CsTaSi, and CsTaGe, have been investigated using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method within the density functional theory (DFT). The volume-optimization graphs show that all compounds are stable in the ferromagnetic (FM) phase. Half-Metallicity of these compounds is confirmed by the density of states (DOS) and band structures. The total magnetic moment for CsTaC is 6 μB, and for CsTaX (X = Si, Ge) is 2 μB. The negative pd exchange energy and exchange constants confirm ferromagnetism. The values of Pugh’s ratio (B/G) and Poisson’s ratio (v) reveal that CsTaC is ductile and CsTaX (Si, Ge) is brittle. The thermoelectric response is estimated using the BoltzTraP code, demonstrating that at room temperature, maximum ZT values for CaTaC, CsTaSi, and CsTaGe are 0.99, 0.97, and 0.90, respectively. Consequently, CsTaX (X = C, Si, and Ge) are suitable candidates for spintronic and thermoelectric technologies.

Exploring Polymorphism in Quinoline‐4‐Carbaldoxime: Experimental Validation and Computational Insights into Hydrogen Bonding and Structural Variations

AbstractThis study identifies and characterizes a second polymorph (Poly‐II) of quinoline‐4‐carbaldoxime (HQ), isolated from an acetone‐acetonitrile mixture. Poly‐II was compared to the previously known Poly‐I using PXRD, DSC, IR, and Raman spectroscopy. Poly‐I forms a 1D supramolecular assembly, whereas Poly‐II exhibits a 2D assembly with additional hydrogen bonds. Hirshfeld surface analysis reveals the presence of different non‐covalent interactions in Poly‐I and Poly‐II, and atom‐in‐molecule (AIM) analysis identifies their strength. AIM analysis, along with Espinosa's relation, was used to calculate the strength of O─H···N and C─H···N interactions in Poly‐I and Poly‐II. The values are −30.0 and −6.17 kJ/mol for Poly‐I, whereas the values for Poly‐II are −36.18 and −3.66 kJ/mol. The plane wave periodic DFT calculations determined the lattice energies of Poly‐I and Poly‐II to be −1.52 and −1.53 eV, respectively, indicating that both polymorphs have comparable stability. The crystal parameters of Poly‐I and Poly‐II obtained from theoretical simulations and the experiment are comparable, indicating the similar stability of Poly‐I and Poly‐II. Computational simulations confirmed experimental data, showing both polymorphs have similar stability and melting points despite different unit cell volumes.

Computations of fields induced in biological tissues by electromagnetic (EM) wave in multilayered structure

The assessment of the fields induced in biological tissue by an electromagnetic (EM) wave is a major issue, not only for its relevance in medical research, but also for its implications on the setting of industrial standards. This paper describes the analysis of electromagnetic (EM) absorption properties of biological multilayered structure. The biological structure comprises three different tissues of skin, fat and muscle. A step-by-step approach for the computation of the EM fields within the multilayered structure is presented. The estimated specific absorption rate (SAR) distribution in tissues due to exposure from plane waves of frequencies 433, 900, 1300, 1800, and 2450 MHz, based on an incident power density 4.5 [mW/cm2], are also presented.

First principles calculations of double perovskite RbX2Y3O10 (X = Ca, Ba: Y[dbnd]Cd, Ta) materials for photocatalytic applications

Production of oxygen and hydrogen energy through suited photocatalysts by water splitting is the main issue in the modern age. In this regard, the double perovskite Dion-Jacobson materials RbX2Y3O10 (X = Ca, Ba: YCd, Ta) for photocatalytic activity are investigated by using the CASTEP package. The plane-wave (PW) pseudo-potential in the context of the generalized gradient approximation (GGA)-Perdew Burke Ernzerhof (PBE) and local density approximation (LDA) exchange-correlation functional technique is used to investigate the compounds. According to the results, compounds have a tetragonal (a = b≠c) structure with space group 123 (p4/mmm). Compounds Mullikan bond populations were estimated in order to comprehend the bonding characteristics that found a mixed ionic and covalent bonding. According to electronic characteristics, RbBa2Ta3O10, RbBa2Cd3O10, and RbCa2Cd3O10 have semiconductor behavior with indirect bandgap of 2.11 eV, 2.27 eV, and 1.51 eV, respectively, and respond under visible region light. DOS and PDOS are studied to inspect the distinct atom's contribution to electronic band structure. The compounds are mechanically brittle (1.55, 1.39), ductile (1.97), and stable in their natural form, according to elastic constant values. The optical characteristics simulation indicates that compounds have the potential to decompose or oxidize organic contaminants. According to the results, these compounds are suitable for the water-splitting photocatalytic process to produce oxygen and hydrogen.

Ab initio study of iron-doped zinc oxide for efficient dye degradation

First principle calculations were performed on iron doped zinc oxide (Fe-ZO) to reduce its bandgap to optimize its visible light absorption. The doping of iron in the ZO is done via supercells of Zn1-xFexO. The doped systems are analyzed using generalized gradient approximation plane wave pseudopotential on density functional theory, or local density approximation and LDA + U with PBE. The computational analysis reveals that the bandgap reduced with increasing dopant concentration. Furthermore, a robust absorption is observed toward the visible region of the spectrum. This enhances its ability as a photochemical material to increase degradation rates of industrial grade dyes.

Electronic structure of ultrathin single-walled platinum nanotubes

Using Density Functional Theory based on the plane wave method and linearized augmented cylindrical wave method, and taking into account the spin–orbit interaction, the structural, electronic and spin properties of ultrathin single-walled nanotubes consisting of six platinum rows are obtained. The nanotubes are found to possess metallic electronic mobility, including the nonchiral Pt(6,0) with the largest number (15G0) of ballistic channels. Analysis of the density of electronic states at Fermi level revealed that the chiral Pt(5,1) has a difference in concentration of mobile electrons with opposite spins of 1.42 times, and up to 3–4 times under a weak torsional strain.

Unveiling the Loss Mode Enabled Tunable Plasmonic Chirality at Flat Metal Surface.

Plasmonic chirality has garnered significant interest in the past decade due to its enhanced chiral light-matter interactions. Current methods for achieving plasmonic chirality often rely on complex nanostructures or metamaterials, which are hampered by intricate fabrication processes. In this work, we present an approach to generate plasmonic chiral structured surface plasmon polariton (s-SPP) fields on a single, flat metal surface, bypassing elaborate fabrication techniques. The plasmonic chiral s-SPP fields are excited by the superposition of multiple differently oriented transverse magnetic polarized plane waves. We demonstrate, both theoretically and experimentally, the flexible tuning of chiral plasmonic patterns by adjusting the symmetry and phase differences of the incident waves. This method provides a facile mean to optically tailor plasmonic chiral properties on a subwavelength scale, offering potential applications in sensing, enantioselective reactions, imaging, and reconfigurable chiral switches.

Investigation of structural, electronic, optical, and mechanical properties of perovskite CsPbBr3 material through induced pressure for photovoltaic applications: A DFT Insights

Herein, perovskite CsPbBr3 material was computationally explored at pressure limits from 0.0 to 8.0 GPa using a 5-step (2GPa gap) calculation. CASTEP (Cambridge Serial Total Energy Package) program is used which is based on density functional theory (DFT), with an ultra-soft (US) pseudo-potential (SP) plane wave and the GGA-PBE exchange–correlation functional. When the pressure increases from 0.0 to 8.0 GPa, the bandgap decreases from 1.84 to 0.60 eV. In comparison to higher pressures, the bandgap decreases significantly until 8.0 GPa. The mechanical properties of the compound at various pressures are also investigated, which indicates that the compound is mechanically ductile and stable in nature. Various optical characteristics, such as the refractive index, loss function, absorption coefficient, and reflectivity, have been determined under pressure limits from 0.0 to 8.0 GPa. For solar cell applications, a compound with high absorption, refractive index, and optical conductivity is optimal.

Analysis of the electronic nature and transport properties of Co2CrGe, Co2FeGe, and Co2NiGa by computational electronic structure calculations

AbstractElectronic and thermoelectric properties of the full‐Heusler materials Co2CrGe, Co2FeGe, and Co2NiGa are studied, using first‐principles full potential linearized augmented plane waves method. To treat the exchange correlation, Generalized Gradient Approximation parameterized by PBE‐sol with the inclusion of spin polarization is used. The frequency fluctuation order is continual at 300 K after heating to 3 ps with very small distraction in the atomic structure conforming the structure stability of the studied structures. Also inclusion of spin‐orbit coupling effect on density of states undermines significant change in peaks specially d‐states in the materials and caused a degeneracy. Band structure analysis clarified that states crossing the Fermi level have the importance for enhancing the thermoelectric properties of the materials. The topology of the states indicates a gap at the bulk level, which is the unique character of the heavy elements in the materials Co2CrGe, Co2FeGe, and Co2NiGa. Thermoelectric properties are calculated for a temperature of 300 K using semi‐classical Boltzmann's theory implemented in BoltzTraP code. In these calculations, it is found that these materials favor electron doping with having maximum values of ZT in the n‐type region.

Theoretical Studies of the Electronic and Thermoelectric Properties of PrIn3 and NdIn3 in Cubic Phase

The electronic and thermoelectric properties of AB3 (A =Pr, Nd and B=In) materials (crystallizing in the cubic structure) having space group Pm-3m (221) are studied using B3PW91 hybrid functional through the Full-Potential Linear Augmented Plane Wave (FP-LAPW) approach within the framework of Density Functional Theory (DFT). The calculated lattice parameters for PrIn3 and NdIn3 are 4.5668 Å and 4.5539 Å respectively. Electron-electron correlation effect is due to the 4f orbitals present in these materials and therefore, with the use of B3PW91 hybrid functional, band structure and density of states are calculated. When analyzing electron charge density, these materials showed a stronger ionic character. Band structure and density of state analysis confirms the metallic nature of the materials. Using the semi-empirical Boltzmann approach implemented in the BoltzTraP code, the thermoelectric parameters, such as Seebeck coefficient, figure of merit, electrical conductivity per relaxation time, and electronic thermal conductivity per relaxation time as a function of chemical potential, were computed at 500 K temperature gradient. PrIn3 showed highest Seebeck coefficient value, 50.68 μV/K among these compounds. The peak value of electrical conductivity per relaxation time and electronic thermal conductivity per relaxation time among these compounds is calculated for NdIn3 is 2.43 x 1020 1/Ωms and 22.50×1014 W/mKs.

Quasinormal modes and universality of the Penrose limit of black hole photon rings

We study the physics of photon rings in a wide range of axisymmetric black holes admitting a separable Hamilton-Jacobi equation for the geodesics. Utilizing the Killing-Yano tensor, we derive the Penrose limit of the black holes, which describes the physics near the photon ring. The obtained plane wave geometry is directly linked to the frequency matrix of the massless wave equation, as well as the instabilities and Lyapunov exponents of the null geodesics. Consequently, the Lyapunov exponents and frequencies of the photon geodesics, along with the quasinormal modes, can be all extracted from a Hamiltonian in the Penrose limit plane wave metric. Additionally, we explore potential bounds on the Lyapunov exponent, the orbital and precession frequencies, in connection with the corresponding inverted harmonic oscillators and we discuss the possibility of photon rings serving as effective holographic horizons in a holographic duality framework for astrophysical black holes. Our formalism is applicable to spacetimes encompassing various types of black holes, including stationary ones like Kerr, Kerr-Newman, as well as static black holes such as Schwarzschild, Reissner-Nordström, among others.

Exciting topological edge states by using plane waves in valley-Hall photonic crystal slabs

Topological edge states are commonly excited by dipole sources or waveguide couplers. In practice, however, such near-field excitations are unfavorable and the simplest way is to use far-field sources. In this report, we theoretically show that the topological edge modes inside the light cone can be directly excited by plane waves via momentum matching, taking valley-Hall topological photonic crystal slabs as examples. Due to the field distributions and mode symmetries, the edge states show different excitation behaviors. One of the edge modes behaves as symmetry-protected bound states in the continuum (BIC) and is excited only by oblique incidence, the Q-factor of which diverges to infinity for normal incidence and drastically decreases for the increase of incident angle. The other one, however, can be excited by far-field for arbitrary incident angle, which does not show the influence on the magnitude of Q-factor. By changing the incident angle, the resonant wavelengths of both modes are tunable and they are determined by the edge bandstructure. Due to the simple excitation scheme and high Q-factors of excited edge states, this proposal will find practical applications, including efficient frequency conversion, sensing, slow light, and optical communications.

Thermoelectric and optoelectronic features of C- and N- doped CsZnBr3 halide perovskite for use in spin filter and energy efficient devices

Present study reports mainly thermoelectric and optical properties followed by its structural, electronic, magnetic properties of CsZnBr3 halide perovskite using full potential linearized augmented plane wave method in the framework of density functional theory. Further we analyzed the impact of C and N on CsZnBr3 for their electronic structure, magnetic nature, thermoelectric, and optical properties. CsZnBr3 under optimum conditions exhibits a non-magnetic phase, which interestingly upon doping of C and N, turns out to be ferromagnetic with magnetic moments of 3.0 and 2.0 μB for CsZnBr2C and CsZnBr2C, respectively. Furthermore, Semiconducting CsZnBr3 exhibits spin filter semiconductor nature with energy band gaps of 1.38↑ and 3.26↓ eV for CsZnBr2C and 2.72↑ and 1.67↓ eV for CsZnBr2N. These doped materials can be used in spintronics as spin-filter devices for lower power consumption leading to more energy-efficient electronics. The thermoelectric parameters as Seebeck coefficient, power factor, thermal conductivity and figure of merit are estimated using BoltzTrap code. The figure of merit value found enhanced from 0.88 to 1.06 with one orientation of spins for CsZnBr2C at high temperature, which suggests its potential use in thermoelectric applications. In optical reference photon energy can be absorbed in UV-region.

Investigating the optoelectronic properties of Mn and Fe doped CuAlS₂ for intermediate band solar cell applications

Chalcopyrites demonstrate compelling features for optoelectronic and photovoltaic devices, attributed to their valuable properties. Their remarkable light-absorption capabilities and well-suited band gap render them so attractive for applications in these fields. By allowing low-energy sub-bandgap photons to pass through and reducing the thermalisation loss from high-energy photons, intermediate-band materials address the primary problems in solar cells. This approach allows for more efficient use of the solar spectrum, helping solar cells exceed the traditional efficiency limits defined by the Shockley-Queisser limit. The objective of this study was to evaluate the electronic and optical characteristics of CuAlS2 systems doped with transition metals (TM = Mn, Fe) using the Full Potential Linearized Augmented Plane Wave approach within the framework of Density Functional Theory. A stable phase within the systems was observed upon replacing the Al atom with TM. The functionality of the intermediate band was governed by the 3d electronic characteristics of the TM3+ ion and its electronic configuration. The optical properties of CuAlS2 doped with Mn and Fe were analysed by calculating the dielectric function, refractive index, reflectivity, and absorption coefficient. Furthermore, the introduction of Mn and Fe through doping led to the creation of an intermediate band, enhancing visible light absorption and power conversion efficiency. Consequently, the optical spectrum of Mn-doped CuAlS2 and Fe-doped CuAlS2 compounds exhibits additional absorption peaks, accompanied by a significant improvement in absorption intensity. Our findings highlighted the need for continued and futuristic research into the scalability of these materials for practical applications in solar cells, optoelectronics, and spintronic devices. This investigation suggests that Mn-doped CuAlS2 holds the highest potential due to its high charge carriers and low recombination rate, indicating enhanced performance in CuAlS2-based intermediate band solar cells.

Scattering characteristics of dual counter-propagation high-order circularly symmetric Bessel beam by a multilayer chiral sphere

The interaction between dual counter-propagating high-order circularly symmetric Bessel beams (CSBBs) and multi-layered chiral particles is investigated. Within the framework of generalized Lorenz-Mie theory (GLMT), the distribution characteristics of the superposition of two beams are studied based on the vector superposition theorem. The near-field, internal field, and far-field radar cross section (RCS) of the dual-layered chiral sphere illuminated by dual CSBBs are obtained according to the boundary conditions. By comparing the results of RCS with those from the references for two cases: first, when CSBBs degenerate into plane waves incident on multi-layered chiral sphere, and second, when Bessel beams illuminate isotropic multi-layer sphere degenerated by chiral multi-layered sphere, the effectiveness of the principle and program exhibited here is confirmed. The impact of various parameters on the distribution of the superposed field, the near-field, internal field, and far-field RCS of the particles are analyzed in detail, such as the order, half-cone angle, incidence angle, and polarization angle. The research results in this paper provide theoretical assistance for understanding the interaction between dual CSBBs and non-uniform chiral multi-layered particles and have important value in realizing optical manipulation of complex chiral layered particles.

Study of the fundamental physical characteristics of the Zintl phase K2BaCdSb2

The structural, elastic, thermodynamic, electronic, and thermoelectric characteristics of K2BaCdSb2 were investigated utilizing ab initio methods. The structural, elastic, and thermodynamic properties were calculated using the pseudopotential plane wave approach with the GGA-PBEsol exchange-correlation functional. The computed equilibrium structural characteristics closely match the available data. The anticipated elastic constants reveal that K2BaCdSb2 is mechanically stable, brittle, and exhibits significant elastic anisotropy. The full potential linearized augmented plane wave approach with the Tran-Blaha modified Becke-Johnson potential was used to determine the electronic structure of K2BaCdSb2.It is found that K2BaCdSb2 is a semiconductor with a Γ-Γ type direct bandgap of 0.85 eV. Bonding analysis shows the bond between Cd and Sb atoms within the [CdSb2]4− polyanion is of covalent nature and that between the K/Ba atom and the [CdSb2]4− polyanion is of ionic character. The thermoelectric characteristics of K2BaCdSb2 were analyzed at a temperature of 500 K for of charge-carrier concentrations from 1 × 1018 to 3 × 1020 cm−3.When the concentration of holes is 1.0 × 1020 cm−3, The power factor reaches a value of 17 × 1010 W m−1 K−2.s−1 for a hole concentration of 1.0 × 1020 cm−3. For the p-doped K2BaCdSb2 with a concentration of 1.0 × 1018cm−3, the electronic figure of merit is 0.95.

Reflection of plane waves in an initially stressed rotating nonlocal micropolar transversely isotropic generalized thermoelastic medium

Reflection of plane waves in an initially stressed rotating nonlocal micropolar transversely isotropic generalized thermoelastic medium

Isolated Spiral Solutions of the Ginzburg–Landau Equation

Using finite element simulation, we study the main features of rotating wave solutions of the cubic complex Ginzburg–Landau equation. To focus on the characteristics of the waves themselves, we have used a circular domain to avoid the effects of irregular boundaries; we have inhibited the formation of defects using an Archimedean wave centered at the origin as the initial condition, and we have chosen a domain size long enough to contain several spiral arms but not so long as to promote long-wave instabilities. This allows us to focus on the geometric features of the solutions often overlooked in traditional works with random initial conditions in large domains. We show with our simulations that the convective and absolute stabilities differ from those predicted for plane waves. Likewise, we show that the appearance of spirals and anti-spirals can occur in any of the quadrants of the parameter space and depends fundamentally on the initial conditions. Finally, regarding the stability of spiral waves against sideband disturbances, we show that the persistence of two-dimensional spiral waves, if fulfilled, does not correspond to the Eckhaus criterion. Our simulations allow us to corroborate the idea that two-dimensional spirals depend on the size of the domain and that they require new analytical results whose trends are identified in this work.