Constant External Electric Field Research Articles

Rotation Matrix of a Charged Symmetrical Body: One-Parameter Family of Solutions in Elementary Functions

Euler–Poisson equations of a charged symmetrical body in external constant and homogeneous electric and magnetic fields are deduced starting from the variational problem, where the body is considered as a system of charged point particles subject to holonomic constraints. The final equations are written for the center-of-mass coordinate, rotation matrix and angular velocity. A general solution to the equations of motion is obtained for the case of a charged ball. For the case of a symmetrical charged body (solenoid), the task of obtaining the general solution is reduced to the problem of a one-dimensional cubic pseudo-oscillator. In addition, we present a one-parametric family of solutions to the problem in elementary functions.

Fermionic condensate and the vacuum energy-momentum tensor for planar fermions in homogeneous electric and magnetic fields

We consider a massive fermionic quantum field localized on a plane in external constant and homogeneous electric and magnetic fields. The magnetic field is perpendicular to the plane and the electric field is parallel. The complete set of solutions to the Dirac equation is presented. As important physical characteristics of the vacuum state, the fermion condensate and the expectation value of the energy-momentum tensor are investigated. The renormalization is performed using the Hurwitz function. The results are compared with those previously studied in the case of zero electric field. We discuss the behavior of the vacuum expectation values in different regions for the values of the problem parameters. Applications of the results include the electronic subsystem of graphene sheet described by the Dirac model in the long-wavelength approximation.

Pure elongation flow of an electrorheological fluid: insights on wall slip from electrorheology.

In this work we study the pure elongation flow behavior of an electrorheological (ER) fluid as a model soft-jammed system, wherein the extent of jamming is controlled by an externally applied electric-field. More specifically, a pure elongation flow has been achieved by facilitating significant slip at the contact between the material and rheometer-plate while pulling it with constant pulling velocity under a constant external electric-field. The normal force exerted by the top plate on the material was measured as a function of gap during the flow for various combinations of electric-field strength and pulling velocity. For any force-gap curve, at first force increases to the maximum (region-I), then it decreases with gap (region-II). In region-II, the normal force-gap curve shifts to higher gaps with increasing electric-field strength for any given pulling velocity. Interestingly, these curves (region-II) demonstrate gap-electric field-velocity superposition, manifesting the self-similar nature of the flow. Finally, we have modeled the flow curves using a slip-layer model, which rendered a remarkable prediction of flow curves and also led to estimation of slip-layer thickness. We observed that slip-layer thickness decreases with increasing magnitude of electric field for a given pulling velocity, which suggests that the extent of jamming plays a crucial role in slip dynamics.

Optical gain and entanglement through dielectric confinement and electric field in InP quantum dots.

Quantum dots are widely recognized for their advantageous light-emitting properties. Their excitonic fine structure along with the high quantum yields offers a wide range of possibilities for technological applications. However, especially for the case of colloidal QDs, there are still characteristics and properties which are not adequately controlled and downgrade their performance for applications which go far beyond the simple light emission. Such a challenging task is the ability to manipulate the energetic ordering of exciton and biexciton emission and subsequently control phenomena such as Auger recombination, optical gain and photon entanglement. In the present work we attempt to engineer this ordering for the case of InP QDs embedded in polymer matrix, by means of their size, the dielectric confinement and external electric fields. We employ well tested, state of the art theoretical methods, in order to explore the conditions under which the exciton-biexciton configuration creates the desired conditions either for optical gain or photon entanglement. Indeed, this appears to be feasible for QDs with small diameters (1 nm, 1.5 nm) embedded in a host material with high dielectric constant and additional external electric fields. These findings offer a new design principle which might be complementary to the well-established type II core-shell QDs approach for achieving electron-hole separation.

Scalar particle creation in a quantum gravity perspective

In gravity’s rainbow perspective (GRP), we intend to analyze the particle production coming from electromagnetic and gravitational fields of the spin-0 (scalar) particles. In accordance with this purpose, a constant external electric field is taken into account together with a rainbow metric with non-isotropic expansion. We obtain the number density of the created Klein–Gordon particles in terms of particle mass, particle charge, external electric field parameter, rainbow functions and particle momentum by using the Bogoliubov transformation method. We display that the number density of the created scalar particles becomes thermal both in the absence of the external constant electric field and in the massless case. We also provide a graphical analysis to scrutinize the particle creation process in the GRP. In this context, it has been observed that rainbow functions drastically alter the number density of the created scalar particles.

Effect of the Applied Electric Field on the Thermal Properties of the Relativistic Harmonic Oscillator in One Dimension

We study the relativistic harmonic oscillators (Dirac and Klein–Gordon ones) in a constant external electric field. The solutions obtained are exact. These solutions allowed us to focus on the effect of the external electric field on the thermal properties of such oscillators. These properties are calculated by means of the Zeta-based method. Some figures have been built to show the mentioned effect.

Electroacoustic Effect and Electrical Superconductivity of Metals

The paper discusses the conditions under which superconductivity of metals would be detected at atmospheric pressure and at room temperature. One of the possible directions of research to achieve these conditions is to change the phonon spectrum of metals in order to increase the Debye temperature, and therefore to increase the temperature of the superconducting transition Tc. According to the idea of the work and to the estimates made in it, the maximum frequency of phonons nmax in metals can be increased by the short-term action of an external constant electric field (electric pulse). The duration of the pulse should be (10–5–10–7) s. The voltage of the constant electric field source is U » 1V. A decrease in the crystal lattice parameter should be accompanied by an increase in the maximum phonon frequency nmax and, accordingly, by an increase in the Debye temperature. The characteristic size of the sample, in which the change in electron concentration can be realized, should not exceed the length of electron shielding in metals, i. e. ≈ 10–8 m. The sequential action of a certain number of electric field pulses can maintain a superconducting state in a metal sample for some finite time.

Investigating simultaneous effects of temperature, surface heterogeneity and geometry on fluid mixing in electroosmotic flow considering temperature dependent properties by Nernst–Planck Poisson method

Numerical study of the effect of temperature and heat transfer as well as surface heterogeneity effects on mixing and electroosmotic flow in microchannels with convergent/divergent and straight mixing chamber is carried out. The fluid properties and surface zeta potentials are assumed to be temperature dependent. Based on the Nernst–Planck Poisson model, the governing equations of this problem include the Laplace equation, Poisson equation, Navier–Stokes and the propagation equation as well as the energy equation, respectively for the distribution of external electric field, distribution of internal electric field due to the charge of ions, fluid motion, concentration field and temperature distribution, which are solved by the finite element method. Flow rate, the mixing efficiency and a new parameter called mixing capacity, which is achieved by multiplying flow rate by mixing efficiency, are obtained for convergent/divergent and straight microchannels in a constant external electric field distributed under different wall temperatures, and performance of the geometries in flow transfer and mixing development is investigated. For electroosmotic flow, heterogeneous microchannels create vortices which improve mixing. Different arrangements of heterogeneous pieces of the surface create different patterns of vortices, each of which has different effects in the various geometries on fluid flow and mixing. Also, the dependence of the molecular diffusion on temperature causes increasing the mixing of species with the temperature increment. The results show that divergent microchannels have the maximum flow rate and the minimum mixing efficiency, but this efficiency can be increased by increasing the wall temperature. Convergent microchannels also have high mixing efficiency due to low flow rates and sufficient time for mixing even at low and near ambient temperatures, although their mixing capacity is less than the divergent microchannels.

The frequency of current fluctuations in two-valley semiconductors in an external electric and strong magnetic (

Boltzmann's kinetic equations have not been used to date to study nonequilibrium phenomena in semiconductors, and therefore, to obtain analytical expressions for the oscillation frequency inside the semiconductor and the critical external electric field, it is of theoretical interest. In this theoretical work, the frequency of oscillations occurring inside a two-valley semiconductor of the GaAs type in an external constant electric field and in an external strong magnetic field (

Atomic Force Microscopy Study of the Effect of an Electric Field, Applied to a Pyramidal Structure, on Enzyme Biomolecules.

The influence of an external constant strong electric field, formed using a pyramidal structure under a high electric potential, on an enzyme located near its apex, is studied. Horseradish peroxidase (HRP) is used as a model. In our experiments, a 27 kV direct current (DC) voltage was applied to two electrodes with a conducting pyramidal structure attached to one of them. The enzyme particles were visualized by atomic force microscopy (AFM) after the adsorption of the enzyme from its 0.1 µM solution onto mica AFM substrates. It is demonstrated that after the 40 min exposure to the electric field, the enzyme forms extended structures on mica, while in control experiments compact HRP particles are observed. After the exposure to the electric field, the majority of mica-adsorbed HRP particles had a height of 1.2 nm (as opposed to 1.0 nm in the case of control experiments), and the contribution of higher (>2.0 nm) particles was also considerable. This indicates the formation of high-order HRP aggregates under the influence of an applied electric field. At that, the enzymatic activity of HRP against its substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) remains unaffected. These results are important for studying macroscopic effects of strong electromagnetic fields on enzymes, as well as for the development of cellular structure models.

Janus Type Monolayers of S-MoSiN2 Family and Van Der Waals Heterostructures with Graphene: DFT-Based Study.

Novel representative 2D materials of the Janus type family X-M-ZN2 are studied. These materials are hybrids of a transition metal dichalcogenide and a material from the MoSi2N4 family, and they were constructed and optimized from the MoSi2N4 monolayer by the substitution of SiN2 group on one side by chalcogen atoms (sulfur, selenium, or tellurium), and possibly replacing molybdenum (Mo) to tungsten (W) and/or silicon (Si) to germanium (Ge). The stability of novel materials is evaluated by calculating phonon spectra and binding energies. Mechanical, electronic, and optical characteristics are calculated by methods based on the density functional theory. All considered 2D materials are semiconductors with a substantial bandgap (>1 eV). The mirror symmetry breaking is the cause of a significant built-in electric field and intrinsic dipole moment. The spin-orbit coupling (SOC) is estimated by calculations of SOC polarized bandstructures for four most stable X-M-ZN2 structures. The possible van der Waals heterostructures of considered Janus type monolayers with graphene are constructed and optimized. It is demonstrated that monolayers can serve as outer plates in conducting layers (with graphene) for shielding a constant external electric field.

Spin dependent polarization response in HgCdTe hot-electron bolometers

The paper reports the detection of strong polarization-dependent photo-responses in direct narrow-gap (Eg = 0.084 eV at T = 80 K) HgCdTe thin-layer biased and unbiased hot-electron bolometers (HEBs) with receiving antennas under elliptically polarized THz radiation. The observed effects are assumed to be due to the Rashba spin splitting in HgCdTe, caused by large spin-orbit interactions. The studied detectors demonstrate free-carrier polarization-dependent sensitivity to laser radiation with h 0.0044 eV (ν = 1.07 THz) and 0.0025 eV (ν = 0.6 THz), i.e., with photon energies much less than the band-gap (hν << Eg) at T = 80 and 300 K. The polarization-dependent photocurrent in HgCdTe HEBs with and without applied external constant electric field is shown to have angular dependence of photocurrent with directional reversal on switching the photon helicity.

Thermoelectric phenomena in a one-dimensional diffusive quantum medium

The quantum diffusion in a one-dimensional lattice in a tunneling regime under the influence of spatially inhomogeneous Gaussian noise is studied theoretically. It is shown that the thermopower appears at an arbitrary value of the tunneling coupling. In the strong tunneling regime at an extremely high temperature, when the drift component of the charge transport can be neglected, the thermoelectric effect takes place only in the presence of a constant external electric field. The Seebeck and Peltier coefficients for the closed-circuit mode are obtained for a one-dimensional quantum diffusion medium in the tunneling regime. In the strong tunneling regime, both the thermopower and the Peltier effect are essentially nonlinear phenomena.

Renormalons in a scalar self-interacting theory: Thermal, thermomagnetic, and thermoelectric corrections for all values of the temperature

In this article we revisit the discussion of renormalons in the frame of a scalar self-interacting $\lambda \phi^{4}$ theory in the presence of thermomagnetic effects, i.e magnetic and thermal effects. Our results for the evolution of the residues is now given by an explicit analytic expression, valid for all values of temperature, without the necessity of separating the discussion in a low- and a high temperature region analyses. We carry out the same discussion for the case of an external constant electric field, obtaining also in this case an analytic expression for the whole range o temperature. In both cases, the location of the poles in the Borel plane does not change with respect to the vacuum case. Their residues, however, acquire a dependence on temperature and the external field. Results are presented for the evolution of residues in the thermomagnetic and thermoelectric cases. We show a comparison with our previous results in the thermomagnetic case, presenting also in detail the mathematical techniques needed for our analytic expressions to be valid in the whole range of temperature.

Catalysis and inverse electric catalysis in a scalar theory

In this article we explore the phase diagram associated to the symmetry breaking of a scalar self-interacting theory, induced by temperature and the presence of an external electric field. For such purpose, first we obtain the boson propagator, in the presence of a constant external electric field, both in the weak and strong field strength limits. Novel expansions are derived for the effective potential, valid for the whole range of temperature. We found inverse electric catalysis for the weak field region, i.e., a situation where the critical temperature diminishes as function of the strength of the electric field whereas for a strong field electric catalysis emerges. These behaviors, in the weak and strong intensity sectors, are valid for all possible values of temperature.

Generation of unipolar pulses of terahertz radiation with a large electric area

A physical situation is proposed and theoretically analyzed, in which, in our opinion, it is possible to generate unipolar terahertz pulses with a large electric area. In this case, the gas in the tube is excited by a femtosecond IR laser pulse. In this case, the tube with gas is placed in a constant external electric field. The generation of a unipolar pulse is based on "three-step scheme" --- ionization of gas atoms by a femtosecond pulse, subsequent acceleration of a free electron in a dc external field and subsequent annihilation of an electron upon collision with a tube wall or another atom (ion). Keywords: unipolar pulses, ultrafast optics, electric pulse area, terahertz radiation, three-step model.

Генерация униполярных импульсов терагерцового излучения с большой электрической площадью

A physical situation is proposed and theoretically analyzed, in which, in our opinion, it is possible to generate unipolar terahertz pulses with a large electric area. In this case, the gas in the tube is excited by a femtosecond IR laser pulse. In this case, the tube with gas is placed in a constant external electric field. The generation of a unipolar pulse is based on ”three-step scheme" - ionization of gas atoms by a femtosecond pulse, subsequent acceleration of a free electron in a dc external field and subsequent annihilation of an electron upon collision with a tube wall or another atom (ion).

Dependence of the energy of emission molecular orbitals in short open carbon nanotubes on the electric field

On the examples of short open carbon nanotubes of armchair type (n,n), for n=3, 4, and zigzag (n,0), for n=5, 6, 7, the influence of the magnitude and direction of the external constant electric field vector on their field emission properties was studied. It is shown that the deviation of the field vector from the nanotube axis leads to an increase in the field strength to generate electron field emission. Emission orbitals in carbon nanotubes (n,n) found as a result of a new type of conjugation of p-electrons in cylindrical conjugated systems are more sensitive to a change in the direction of the electric field vector compared to emission orbitals in nanotubes (n,0). When the electric field vector deviates from the nanotube axis, the emission orbitals of carbon nanotubes change the less, the larger the nanotube diameter. Keywords: short open carbon nanotubes, field emission, conjugation of p-electrons, emission molecular orbital.

THz polarization-dependent response of antenna-coupled HgCdTe photoconductors under an external constant electric field

The photoresponse of antenna-coupled Hg1-x Cd x Te (x ≈ 0.201) narrow-gap epitaxially grown photoconductors with normal band ordering having large spin–orbit coupling and being irradiated by the normal to the photoconductor surface terahertz (THz) radiation (linearly or circularly polarized), is investigated at T = 80 and 300 K. The oscillations of polarized photoresponse in biased and unbised structures were revealed. In experiments, Hg1-x Cd x Te layers (point group ) grown on (013) GaAs substrates were used. In biased structures, to the ordinary charge current and Rashba spin splitting current in zero electric field, an additional polarized current, which grows with the external electric field strength, arises. Presumably, the oscillating photoresponses under polarized THz radiation in these unbiased and biased structures are connected with the circular and linear photogalvanic effects without and with an external electric field. The observed features of the polarized dependent photoresponse can be important for spintronics applications at elevated temperatures.

Spintronics phenomena induced by THz radiation in narrow-gap HgCdTe thin films in an external constant electric field

The responses of uncooled (T = 300 K) and cooled to T = 78 K antenna-coupled Hg1–xCdxTe-based narrow-gap thin-film photoconductors having large spin-orbit coupling and irradiated by the terahertz (THz) radiation (linearly or circularly polarized) have been investigated. Powerful THz radiation excitation causes photocurrents, which signs and magnitudes are controlled by orientation of antenna axes, an external constant electric field direction and orientation of the polarized (circular or linear) radiation electric field falling onto photoconductors. The observed effects seem to be caused by the spin currents observed in devices where spintronic effects are revealed. spintronic phenomena, photoconductors, THz radiation, HgCdTe.