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Diluted magnetic semiconductors are a recent research area due to their ability to enhance ferromagnetic properties and facilitate the electrical detection of magnetoresistance and polarization. (In, Mn)As dilute magnetic semiconductor has potential application in the field of spintronic devices, such as spin field-effective transistors, spin laser light-emitted diodes, modern technology, multi-functional devices, green technology, and nanotechnology. For this study, we have considered the RKKY interaction between Mn2+ spins via delocalized carriers. The effect of manganese ion concentration and applied magnetic field on ferromagnetic diluted magnetic semiconductor properties such as dispersion relation, Curie temperature, and reduced magnetization of (In, Mn)As are studied. We have developed a spin-wave model using the Holstein-Primakaff transformation. Based on the developed model, the number of ferromagnetic magnons, dispersion relations, and Curie temperatures were calculated with or without an applied magnetic field. The reduced magnetization is also calculated. The graph of Curie temperature and magnetization of (In,Mn)As versus temperature with applied field up to 6 T and manganese ion concentration from 0.01 to 0.1 are plotted. The graph of spin wave dispersion of (In,Mn)As versus a wave vector with varying manganese ion concentration with and without an applied magnetic field up to 6 T. In this study, an InMnAs Curie temperature of 290.68 K is found without an applied magnetic field with a 0.1 manganese ion concentration, which is near room temperature. Moreover, with an applied magnetic field of 6 T at 0.1 manganese ion concentration, a Curie temperature of 342.466 K is found, which is above room temperature. Hence, these temperatures are suitable for the field of next-generation spintronic new technology.

The classical problem of geophysical hydrodynamics is the problem of instability of a zonal geostrophic flow with a vertical velocity shear. At present, the instability with respect to symmetric perturbations that do not depend on the coordinate along the flow has been most thoroughly studied. For a symmetric instability to arise, the two-dimensional perturbation wave vector must lie inside a certain sector in the vertical plane of the wave numbers. In this paper, we study the instability with respect to unsymmetric perturbations oriented at an angle to the flow. Fundamentally new features of the temporal dynamics of the amplitudes of such perturbations are found. The main feature is associated with the existence of a stage of exponential explosive growth of finite duration. A kinematic interpretation of this stage is given that is related to the passage of the projection of the three-dimensional wave vector onto the plane transversely to the flow through the sector of symmetric instability. [ABSTRACT FROM AUTHOR]

Electromagnetic ion cyclotron (EMIC) waves play important roles in particle loss processes in the magnetosphere. Determining the evolution of EMIC waves as they propagate and how this evolution affects wave-particle interactions requires accurate knowledge of the wave vector, k. We present a technique using the curl of the wave magnetic field to determine k observationally, enabled by the unique configuration and instrumentation of the Magnetospheric MultiScale (MMS) spacecraft. The wave curl analysis is demonstrated for synthetic arbitrary electromagnetic waves with varying properties typical of observed EMIC waves. The method is also applied to an EMIC wave interval observed by MMS on October 28, 2015. The derived wave properties and k from the wave curl analysis for the observed EMIC wave are compared with the Waves in Homogenous, Anisotropic, Multi-component Plasma (WHAMP) wave dispersion solution and with results from other single- and multi-spacecraft techniques. We find good agreement between k from the wave curl analysis, k determined from other observational techniques, and k determined from WHAMP. Additionally, the variation of k due to the time and frequency intervals used in the wave curl analysis is explored. This exploration demonstrates that the method is robust when applied to a wave containing at least 3-4 wave periods and over a rather wide frequency range encompassing the peak wave emission. These results provide confidence that we are able to directly determine the wave vector properties using this multi-spacecraft method implementation, enabling systematic studies of EMIC wave k properties with MMS.

A tunneling transistor without heterojunction as a theoretical design, or more precisely, the controlled transmission of an electron current through barrier potential, is under consideration. Electrons from the conduction band of the source tunnel through the forbidden gap Eg of the channel to the conduction band of the drain. Calculations of the tunneling current J made at helium temperature for the example structures InAs–InAs–InAs, Au–GaSe–Au, and Al–AlN–Al show that for a constant source–drain voltage, VC, of several mV, changes in the gate voltage, VG, applied to the channel within the voltage range of 0–Eg/2e, change J by even 10 orders of magnitude. Unlike existing solutions, such as the tunnel field-effect transistor, the proposed device uses the change of VG (gate voltage), i.e., a change in the electrostatic potential in the channel, to modify the imaginary wave vector kz of tunnel current electrons. Consequently, the gate voltage controls the damping force of the electron wave functions and thus the magnitude of the tunneling current, J. The effect of increasing temperature T on the relation J(VG) is also tested. It is found that only in the structures with a wide forbidden channel gap this effect is insignificant (at least up to T = 300 K). [ABSTRACT FROM AUTHOR]

Abstract—The article considers a new acoustoelectronic method for measuring the velocity of ultrasonic waves in a liquid. It is shown that by changing the angle between the direction of propagation of an ultrasonic wave and the normal to the surface of a piezoquartz receiver placed in the studied liquid, it is possible determine the propagation velocity of this wave in the liquid. This method has been used at a wave frequency of 3 MHz to measure sound speeds in distilled water, glycerin, and freon. The experimental values of the velocities obtained agree satisfactory with the tabulated data. [ABSTRACT FROM AUTHOR]

Type or paste your abstract here as prescribed by the journal's instructions for authors. Type or paste your abstract here as prescribed by the journal's instructions for authors. Type or paste your abstract here as prescribed by the journal's instructions for authors. Type or paste your abstract here. This paper deals with dynamics of incommensurate superstructure at the moment of its formation. Lyapunov exponent value spectra, phase portraits, incommensurate modulation wave vector behavior, Fourier spectra and maps of incommensurate phase dynamic modes under changed parameters of long-range interaction (Т) and anisotropic interaction (K) in interval 0.0 ÷ 1.0 were analyzed. The calculations were made in Python environment applying Skipy, JiTCODE libraries. Under low values of Т and K parameters (0.0015 ÷ 0.03) a chaotic state occurs in this system. It is determined by the interaction between different spatial areas of the correlated motion of tetrahedral groups. The interaction of spatial areas of the correlated motion of tetrahedral groups violates the modulation pattern of tetrahedral group motion causing the superstructure chaotic state. The study of Fourier spectra has shown that interaction of spatial areas of tetrahedral group correlated motion of causes the chaotic state that is non-stable and is destroyed by long-range interaction. The impact of surface energy on the interaction of spatial areas of tetrahedral group correlated motion is determined by decreased amplitude of vibrations of tetrahedral groups causing the disappearance of the chaotic state. [ABSTRACT FROM AUTHOR]

Anisotropic materials have more unique properties than isotropic materials, and can appear more electromagnetic phenomena. Tn order to study the conditions of transmittance and total penetration angle between anisotropic materials, the dispersion equation of monochromatic plane wave in anisotropic materials is obtained from Maxwelts equations, and the wave vector and Poin are calculated by taking TM wave as an example. The refraction angle of Ting vector found that the wave vector and Poynting vector of ellipsoid surface material are both positive refraction or negative refraction. The relationship between the material transmittance and the incident angle and the total transmission angle found that the ellipsoid material has a transmitted wave and a total transmission angle under the incident angle of the ellipsoid material. The material always has total reflection and no transmittance. The numerical simulation of metamaterials with metal-dielectric multilayer structure supports the conclusion, and it is expected to have a certain reference for related research. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) strongly coupled nonideal plasma systems (SC-NIPSs) are modeled using equilibrium molecular dynamics (EMD) simulations. The dynamical structure factor (DSF) has been investigated under influence of varying wave vectors (k = 2π/L) at high Debye screening (κ) and varying Coulomb couplings (Γ) from nonideal phase to strongly coupled phase. New outcomes of dust DSF S(k,ω) indicate that the frequency of oscillation increases and amplitude decreases with an increase in Γ, respectively, for the SC-NIPSs. The present work shows that the amplitude of dust DSF slightly increases with increasing κ and N, and it also depends on variation of wave vectors. Our investigations demonstrate that the amplitude of oscillation of the dust DSF is changed and shape of spectrum switches from damped oscillation mode to sinusoidal mode with an increase in Γ. These modes of oscillation of dust DSF S(k,ω) shift to higher Γ with increasing κ and N. It has been revealed that the fluctuating density S(k,ω) of dust more oscillates at high Γ and midway value of κ, but this oscillation is less pronounced at high N and κ. The reported simulation data are found to have more precise and well-organized than that of earlier known numerical outcomes and it provides reasonable EMD outcomes with suitable varying N at high screening and large values of Γ than earlier numerical results. [ABSTRACT FROM AUTHOR]

• Large ferromagnetic transition temperature is observed. • The ferromagnetic transition temperature increases nearly linearly with an increase in Mn ion concentration. • The dispersion relation of (In,Mn)As increases with an increase in the manganese ion concentration. Diluted magnetic semiconductors are a recent research area due to their ability to enhance ferromagnetic properties and facilitate the electrical detection of magnetoresistance and polarization. (In, Mn)As dilute magnetic semiconductor has potential application in the field of spintronic devices, such as spin field-effective transistors, spin laser light-emitted diodes, modern technology, multi-functional devices, green technology, and nanotechnology. For this study, we have considered the RKKY interaction between Mn2+ spins via delocalized carriers. The effect of manganese ion concentration and applied magnetic field on ferromagnetic diluted magnetic semiconductor properties such as dispersion relation, Curie temperature, and reduced magnetization of (In, Mn)As are studied. We have developed a spin-wave model using the Holstein-Primakaff transformation. Based on the developed model, the number of ferromagnetic magnons, dispersion relations, and Curie temperatures were calculated with or without an applied magnetic field. The reduced magnetization is also calculated. The graph of Curie temperature and magnetization of (In,Mn)As versus temperature with applied field up to 6 T and manganese ion concentration from 0.01 to 0.1 are plotted. The graph of spin wave dispersion of (In,Mn)As versus a wave vector with varying manganese ion concentration with and without an applied magnetic field up to 6 T. In this study, an InMnAs Curie temperature of 290.68 K is found without an applied magnetic field with a 0.1 manganese ion concentration, which is near room temperature. Moreover, with an applied magnetic field of 6 T at 0.1 manganese ion concentration, a Curie temperature of 342.466 K is found, which is above room temperature. Hence, these temperatures are suitable for the field of next-generation spintronic new technology. [ABSTRACT FROM AUTHOR]

Subject and purpose. The article is devoted to the investigation of the photovoltaic effect in n-InSb under optical transitions between the spin subbands of the Landau levels for the ultraquantum limit. The geometry is considered when the polarization is perpendicular, and the current is directed along the magnetic field. The effect is due to the cubic terms in the Hamiltonian that exist due to the absence of an inversion center. The dependence of the current on the magnetic field has a resonance character. Such an effect is associated with resonance in the intermediate state and interference of the second-order transition amplitudes with respect to relativistic contributions to the Hamiltonian. The aim of the work is a theoretical and experimental study of the photovoltaic effect for spin resonance. Methods and methodology. The photovoltaic effect in optical transitions between the spin-subzones of the Landau le-vels is considered in the article. The geometry of the system under investigation is as follows: the polarization of the electric field is perpendicular, and the current is directed along the lines of force of the magnetic field. Calculation of the magnetic field components and current density was carried out using the finite element method, which is implemented in the ANSYS software. The dependence of the current density on the magnetic field strength is analyzed. This dependence has a resonance character and contains field contributions with even and odd numbers. This effect is associated with resonance in the intermediate state and interference of the amplitudes of relativistic second-order contributions to the Hamiltonian. Results. The practical value and scientific novelty lie in the study of the photovoltaic effect at spin resonance. Since a weakly absorbing medium is considered, an increase in the photovoltaic effect is observed as a result of the divergence of the mean square electric field modulus. The practical significance of the results lies in the development of a methodology for studying band parameters, and the terms in the Hamiltonian can lead to electrodipole transitions and photocurrents. Conclusions. The results of the photovoltaic effect study supplement the experimental measurements of light absorption in a weakly absorbing medium. The same components in the Hamiltonian can lead to electric dipole transitions.

Models of the coupling of electromagnetic and gravitational fields have been studied extensively for many years. In this paper, we consider the coupling between the Maxwell field and the Weyl tensor of the gravitational field to study how the wavevector of the electromagnetic wave is affected by a plane gravitational wave. We find that the wavevector depends upon the frequency and direction of polarization of the electromagnetic waves, the parameter that couples the Maxwell field and the Weyl tensor, and the angle between the direction of propagation of the electromagnetic wave and the coordinate axis. The results show that this coupling model can be tested by the detection of high-frequency gravitational waves. [ABSTRACT FROM AUTHOR]

The size-quantized energy spectrum and the electron wave function in the X3 and X1 subbands of the conduction band of n-GaP are calculated. [ABSTRACT FROM AUTHOR]

Analytical expressions are presented for the wave number, the characteristic wave impedance, and the refractive index of homogeneous longitudinal plane waves propagating in an acoustic metamaterial with dissipative losses. The metamaterial is characterized by the effective scalar material parameters: the complex density and the compressibility. To distinguish between the forward and backward waves, the wave type identifier is introduced. [ABSTRACT FROM AUTHOR]

The Leontovich impedance condition is considered in relation to the boundary with an external isotropic medium characterized by the effective parameters of metamaterials. The surface impedance depends not only on the complex dielectric permittivity and complex magnetic permeability of the substance, but also on the type of the evanescent plane wave. Particular cases of transparent media and media with a balance of electrical and magnetic losses are considered. The conditions for the applicability of the impedance approximation are specified. [ABSTRACT FROM AUTHOR]

In this paper, we shall demonstrate theoretically that steady bound electromagnetic eigenstate can arise in an infinite homogeneous isotropic linear metamaterial with zero-real-part-of-impedance and nonzero-imaginary-part-of-wave-vector, which is partly attributed to that, here, nonzero-imaginary-part-of-wave-vector is not involved with energy losses or gain. Altering value of real-part-of-impedance of the metamaterial, the bound electromagnetic eigenstate may become to be a progressive wave. Our work may be useful to further understand energy conversion and conservation properties of electromagnetic wave in the dispersive and absorptive medium and provides a feasible route to stop, store and release electromagnetic wave (light) conveniently by using metamaterial with near-zero-real-part-of-impedance. [ABSTRACT FROM AUTHOR]