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The investigation delves into the examination of Jeffreys fluid flow within a porous medium, incorporating a temperature-dependent heat source and throughflow, while also taking into account the presence of an external electric field. The eigenfunction, also known as the critical Rayleigh number, is obtained to determine the initiation of convection by employing Galerkin processes during the linear stability analysis. Subsequently, the findings are scrutinized by means of graphical illustrations to explore the impacts of various factors, including the Jeffreys parameter, heat source, throughflow, and electric field. Upon careful examination of the outcomes, it becomes evident that specific parameters, such as the Jeffreys parameter, heat source, and throughflow parameters, exert an influence in stabilizing the system under consideration. The investigation evidently points toward an observation that an augmentation in the electric field parameter results in an accelerated onset of convection. This observation implies that the external electric field assumes a role as a destabilizing element within the system, thereby intensifying the convective tendencies exhibited within the medium. The results demonstrated that elevated throughflow characteristics played a significant role in the postponement of convection onset, while a rise in the heat source parameter dependent on temperature was found to enhance the overall stability of the system. Additionally, it was observed that the downward throughflow exhibited a greater stabilizing influence when juxtaposed with the upward throughflow, particularly in scenarios involving the Jeffreys term and electric fields. The implications of these findings suggest a complex interplay between throughflow parameters, temperature-dependent heat sources, and external forces, highlighting the intricate dynamics governing convection initiation and system stability in the studied environment.

We give a method to obtain estimates on distorted resolvents which we apply to the Stark effect with general potentials. This paper also contains a geometric perturbation theory which together with the estimates mentioned above, shows the existence of resonances and gives an upper bound on the width of resonances in various situations.

The resistive switching effect in TiO_2-x memory devices is thoroughly investigated in order to obtain optimum memory performance, in terms of switching ratio, uniformity of the switching characteristics and multilevel capability. As a result, various fabrication procedures were followed with the aim to enhance the above properties. The main body of our devices was TiO_2-x thin film, with constant thickness of 45 nm, while different approaches were implemented during the fabrication process, such as increasing the oxygen content during film growth, depositing top electrodes with different thicknesses, inserting a layer of nanocrystals (NCs) within the middle of the dielectric and using two various oxygen contents during film deposition in order to create a homobilayer structure. The common feature of these techniques is to control the regions where oxygen vacancy creation will take place in order to control the formation/rupture of the conducting filaments (CFs). Conductive-Atomic Force Microscopy (C-AFM) results support the localized nature of the switching effect. The gradual transition during the SET process, which allows precise CF control through proper external stimulus, as well as the self-rectification effect, which alleviates the sneakpath issue in crossbar architecture, are also important assets of our experimental approach.

The Tantalum oxide material (Ta₂O₅) as tunnel oxide in comparison with the Silicon dioxide (SiO₂) Tunnel oxide is proposed. The lower bandgap and high refractive index of Ta₂O₅ has several advantages over SiO₂. The Ta₂O₅ is used as Anti-Reflecting coating earlier, but also has capability to behave as the tunneling oxide. In the ultrathin region, the Tantalum oxide (Ta₂O₅) potentially produces extremely high tunneling and high electric field. The greater electrical intensity increases both the transportation of carrier and passivation quality of designed c-Si structure. The carrier selectivity is also increased due to very high capacitive nature. The performance measurement is done in ASTM certified AM1.5G environment using Silvaco ATLAS 2D TCAD tool. The comparison has been made between Ta₂O₅ and SiO₂, to show the advantage of Ta₂O₅ over SiO₂. The lower bandgap of 4.8eV and higher affinity of 3.19 of Ta₂O₅ as compared to SiO₂ proves to be better material as tunneling oxide. The bandgap and electric field region of both the materials have been studied. In first approach to use Ta₂O₅ as tunneling oxide, the power conversion 28.42% is obtained for 0.1nm thickness of the Ta₂O₅. External and internal quantum efficiencies are well above 80% and 90% respectively. The characteristics of the Ta₂O₅ tunneling based solar cell are compared with the previous reported solar cell.

There has been considerable interest in non-thermal discharges over the past decade due to the increased number of industrial applications. The properties of discharges in electronegative gases are most frequently used for technological applications. For the improvement of performance in these applications, it is necessary to understand discharge dynamics experimentally and numerically. In this paper, a Monte Carlo simulation is carried out in sulfur hexafluoride (SF₆) in uniform electric fields. The streamer propagation, electron, positive and negative ion distributions and space charge fields are studied in detail as time increases.

The corona discharge commonly occurs in many engineering devices and processes. Their application is still largely based on empirical knowledge; accordingly it is very important to predict the physical properties of corona discharge by the appropriate numerical method. To control corona discharge properly by understanding of corona discharge properties at different discharge stages, time-varying characteristics of discharge which are resulted from electron collision with the gas molecules should be investigated. A numerical study of a corona discharge in nitrogen in a point to plane geometry is presented. It is obtained by Monte Carlo method and concerns space-time evolution of electron and ion densities as well as electric field distributions along the discharge axis.

Using the ab initio plane-wave ultrasoft pseudopotential method based on the generalized gradient approximation (GGA), we investigate the bandgap tuning in monolayer phosphorene in terms of applying external electric fields perpendicular to the layers. The bandgap continuously decreases with the applied electric fields, eventually rendering them metallic. The phenomenon is explained by the giant stark effect. The interlayer P-P distance also result in the semiconductor-to-metal transition. The phosphorene exhibits the significant bandgap tuning ability under different strains with 5% variation. Our investigations show the bandgap change for the fabrication of novel electronic and photonic devices.

In this paper, we consider a square lattice with correlated random hopping terms under the effect of an external electric field. We analyzed the dynamics of an initially localized electronic wave packet using a Taylor formalism to solve the Schrödinger dynamic equation. Our calculations suggest that the correlated disorder promotes a fast electronic propagation for intermediate times. When we switch on a static electric field, we observe an oscillatory behavior similar to the well-known “Bloch oscillations” phenomenology. We calculate the frequency of these oscillations, and our results are in good agreement with those predicted by the semi-classical approach used in crystalline lattices. Based on the local disorder and in the absence of extended states in our model, we discussed the stability of these apparent “Bloch oscillations”.

The scalar particle production from vacuum in the presence of an electric field, on the de Sitter spacetime is studied. We use perturbation methods to define the transition amplitude. We obtain that the momentum is not conserved in this process. The probability density of pair production is computed by squaring the transition amplitude. Our graphical representations show that, the probability of scalar particle production was important only in the early stages of the universe, when Hubble's constant was very large in comparison with the mass of the particle. Also, we propose here a criterion for particle–antiparticle separation.

We elaborate the quasiclassical approach to obtain the modified chiral magnetic effect (CME) in the case when the massless charged fermions interact with electromagnetic fields and the background matter by the electroweak forces. The derivation of the anomalous current along the external magnetic field involves the study of the energy density evolution of chiral particles in parallel electric and magnetic fields. We consider both the particle acceleration by the external electric field and the contribution of the Adler anomaly. The condition of the validity of this method for the derivation of the CME is formulated. We obtain the expression for the electric current along the external magnetic field, which appears to coincide with our previous results based on the purely quantum approach. Our results are compared with the findings of other authors.

We explore the problem of charged perfect fluid spherically symmetric gravitational collapse in f(R, T) gravity (R is Ricci scalar and T is the trace of energy–momentum tensor). We have taken the interior boundary of a star as spherically symmetric metric filled with the charged perfect fluid. In order to study charged perfect fluid collapse, we have investigated the exact solutions of the Maxwell–Einstein field equations solutions using the most simplified form for f(R, T) model f(R, T) = R + 2$\lambda$T, where $\lambda$ is model parameter. This study involves the effects of charge as well as coupling parameter on collapse of a star. We studied the nature of trapped surfaces, apparent horizon and singularity structure in detail. It has been found that singularity is formed earlier than the apparent horizons, so the end state of gravitational collapse in this case is black hole.

In this paper, the propagator of a two-dimensional Dirac oscillator in the presence of a uniform electric field is derived by using the path integral technique. The fact that the globally named approach is used in this work redirects, beforehand, our search for the propagator of the Dirac equation to that of the propagator of its quadratic form. The internal motions relative to the spin are represented by two fermionic oscillators, which are described by Grassmannian variables, according to Schwinger’s fermionic model. Once the integration over the anticommuting variables (Grassmannian variables) is accomplished, the problem becomes the one of finding a non-relativistic propagator with only bosonic variables. The energy spectrum of the electron and the corresponding eigenspinors are also obtained in this work.

The concept of dark matter has been imported to explain the observed velocity profile of the spiral galaxies, the flat rotational velocity. Taking the flatness of rotation curves as an input and assuming that the galactic halo is filled with charged perfect fluid having known mass density function, we obtain a space time metric in the galactic halo region. The acquired solution indicates to a (nearly) flat universe, consistent with the present day cosmological observations. Various other aspects of the solution such as attractive gravity in the halo region, stability of the circular orbit, etc., are also analyzed.

The concept of dark matter (DM) hypothesis comes out as a result from the input of the observed flat rotational velocity. With the assumption that the galactic halo is pseudo-spheroidal and filled with charged perfect fluid, we have obtained a solution which has inkling to a (nearly) flat universe, compatible with the modern day cosmological observations. Various other important aspects of the solution such as attractive gravity in the halo region and the stability of the circular orbit are also explored. Also, the matter in the halo region satisfies the known equation of state which indicates its non-exotic nature.

For type II superconductors, Josephson has shown that vortices moving with velocity v_L create an effective electric field E′= -v_L×B_V. By definition the effective electric field is gradient of the electrochemical potential, what is the quantity corresponding to voltage observed with the use of Ohmic contacts. It relates to the true electric field E via the local chemical potential μ as E′=E-∇μ/e. We argue that at low temperatures the true electric field in the bulk can be approximated by a modified Josephson relation E=(v_S-v_L)×B_V, where v_S is the condensate velocity.

The free polaron energy levels in finite GaAs/Al_xGa_1-xAs parabolic quantum wells have been investigated by a modified variational method. The effect of the electric field, the electron-phonon interaction including the longitudinal optical phonons and the four branches of interface optical phonons, and the effect of spatial dependent effective mass have been considered in the calculation. The dependence of the energies of free polarons on the alloy composition x is given. The numerical results for finite GaAs/Al_xGa_1-xAs parabolic quantum wells are obtained and discussed. The results show that the effect of the electric field and the interface optical phonons as well as the longitudinal optical phonons on the energy levels is obvious. One can find that the effect of the spatially dependent effective masses on the energy levels in finite parabolic quantum wells is considerable except for large well width. Thus, the electron-phonon interaction and the effect of the spatially dependent effective mass should not be neglected for the study of the electron state problem in finite parabolic quantum wells.

Glow discharges are being used in many fields of application. For the improvement of performance in these applications, it is necessary to understand discharge dynamics experimentally and numerically. In this paper, a Monte Carlo simulation is carried out in oxygen (O₂) in uniform electric fields. The electron motion and avalanche growth are simulated by tracing individual paths, and the technique also accounts for the effect of the rapid spatial and temporal space charge variations by solving the Poisson equation. The streamer propagation, electron, positive and negative-ion distribution, and space charge fields are studied in detail as time increases.

The rapidly rotating Bose–Einstein condensate in the presence of an external electric field is studied. The vortex lattice formed in the condensate will shift after the electric field is applied. The electric field changes the particle density distribution and makes the system more stable. A method to detect this shift is also suggested.

The ground-state binding energies of a hydrogenic impurity in cylindrical quantum dots (QDs) subjected to external electric and magnetic fields are investigated using the finite-difference method within the quasi-one-dimensional effective potential model. The QD is modeled by superposing a square-well potential and a strong lateral confinement potential by the combination of a parabolic potential and a changeable magnetic field. We define an effective radius of a cylindrical QD which can describe the strength of the lateral confinement. The effects of the electric fields are less important when the effective radius is very tiny, and the effects are manifested as the effective radius increases. Meanwhile, one finds that the binding energies highly depend on the impurity positions under the applied transverse fields. When the impurity is located at the right half of the cylinder, the electric field pushes the electron to the left side, then the binding energy decreases; when the impurity is located at the left, the binding energy first increases and reaches a peak value, then deceases with the electric field.

A novel temperature-independent superconducting device that employs a doped semiconductor is presented in this study. The underlying theory of this superconductivity is confirmed by experimental results. Specifically, superconductivity generates a negative electric field with characteristics of both electrostatic and current-induced fields. This type of electric field creates a new paired interaction between two electrons and implies the existence of a new force. The negative electric field also exhibits the Meissner effect. Moreover, magnetic flux quanta are produced in the semiconductor. The Aharonov–Bohm effect is exhibited to create a superconducting current along the electric circuit of the superconducting system. Therefore, a load introduced to the circuit will also become superconductive. This finding has strong potential for practical applications. To solve the problem of critical current, a static magnetic field is applied. This field combines with the new electric field to yield cyclotron motion, which increases superconducting current.