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Michael V. Davidovich

Publications and source records attributed to Michael V. Davidovich.

10 recordsLinked to original sources
arXiv2026

Casimir force between plane-layered structures: van Kampen-Schram approach for finite temperature

Based on the van Kampen-Schram method, a formula for the Casimir force between two plane-layered structures is obtained, which includes the sum of the Matsubara frequencies and a contour integral. It is shown that the contour integral is not taken into account in the Lifshitz formula. Taking it into account gives a small contribution at high temperatures when the Lifshitz formula is approximately correct. However, at low temperatures, its contribution is significant, and the Lifshitz formula for the finite temperature does not transform into the Lifshitz formula at zero temperature. An example of interaction of metal plates is considered.1

quant-ph↗
arXiv2026

On Casimir force between two real metallic plates

The corrections to Casimir pressure (force) on two plates of real metal described by the dielectric constant of the Drude, Drude-Lorentz, Drude-Smith and plasma models at the finite temperature and conductivity are considered. We consider the contour integral lost in the Lifshitz formula and discuss inconsistencies for the corrections to the Casimir force given in the literature. Numerical and analytical results in the near and far zones are presented. The two first-order correction obtained due to the actual dielectric constant of the metal coincided with the literature data.

quant-ph↗
arXiv2026

On the Lifshitz formula of dispersion interaction

The Lifshitz formula and methods of its preparation in the literature are considered. It is shown that in Lifshitz's work itself, this formula is given without a consistent conclusion. Moreover, the approach to the conclusion proposed in this work does not allow us to obtain it. The most general conclusion of this formula can be the method proposed by Levin and Rytov, the variation method of Schwinger and the method proposed by Van Kampen and co-authors. The Levin and Rytov approach is applicable in principle to bodies of arbitrary shape if the diffraction loss fields for electric and magnetic dipoles are determined, while the Van Kampen approach is applicable to any plane-layered structure and is quite simple. It is enough to write down the dispersion equations of the plasmon-polaritone structure. The specific dispersion force for a number of structures is calculated based on the Van Kampen method. It is shown that at small gaps, the force (pressure) density changes the inverse fourth-degree dependence on the distance and practically ceases to depend on it at distances less than 1 nm. For thin identical plates, this density is proportional to the square of their thickness at such distances, but the dependence quickly becomes saturated and already at thicknesses of the order of 10 nm practically ceases to depend on it.

quant-ph↗
arXiv2025

On nonlinear graphene response on monochromatic electromagnetic wave in the form as generation of harmonics

We consider the linear and nonlinear response of a weighted graphene sheet under the normal incidence of a plane electromagnetic wave in the form of a quasi-monochromatic pulse of long duration with a sharp edge and harmonic filling. The generation of odd harmonics in the reflected and transmitted spectra is obtained. The coefficient of transformation of the first harmonic into the third harmonic at a frequency of 10 Hz is of the order of 10-3. We use perturbative theory based on the quantum Wallace strong coupling model with field amplitude expansion and integration over the entire Brillouin zone (BZ), solving the kinetic Boltzmann equation with a collision integral in the Bhatnagar-Gross-Crook (BGK) form. The electromagnetic field is considered classically, while its vector potential changes the quasi-pulse in the dispersion equation.

cond-mat.mes-hall↗
arXiv2025

Dispersion and losses of plasmons along simple metasurfaces: the analysis of dispersion equations

The flat metasurfaces described by tensor surface conductivity, the transverse size of which is small compared to the wavelength, are considered. In this case, we introduce two-dimensional surface conductivity for them, as well as for infinitely thin conductive sheets of graphene type. The method of Green's tensor functions of electrodynamics connecting fields and current densities, as well as the mode matching technique, are used. Conductive films on substrates are considered, including layered substrates of finite thickness with periodic layers and infinite substrates, as well as gradient substrates with a dependence of the dielectric constant on the thickness. Two-dimensional periodic structures of conductive films and dielectric films doped with nanoparticles are also analyzed. The possibility of applying the method to diffraction of surface plasmons on metasurface inhomogeneities is analyzed.

cond-mat.mes-hall↗
arXiv2021

Dispersion forces in the Lifshitz problem

We present a sequential derivation of the dispersion forces for the Lifshitz problem, based on the field mode matching technique. The results for the dispersion force on the base of the energy-momentum tensor and the Lorentz force are presented as specral integrals in real domaine.

physics.class-ph↗
arXiv2020

Plasmon-polaritons and diffraction on the layer of asymmetric hyperbolic metamaterial

We consider the plasmon polaritons along a layer of hyperbolic metamaterial propagating in the plane of the anisotropy axis with an arbitrary its orientation. As a layer material, we use periodic plane-layered artificial medium or hyperbolic metamaterial of thin metal and dielectric layers and produce its homogenization. The conditions for the existence of fast, slow, leakage, gliding flowing, forward and backward plasmon-polaritons are found. The Fresnel formulas for the diffraction of a plane wave of arbitrary polarization on such a structure are obtained. The dispersion of plasmon-polaritons and plane wave diffraction are calculated.

physics.optics↗
arXiv2014

Why is the refractive index cannot be negative

It has been shown that for left-handed metamaterials and generally for negative refraction media the refraction index cannot be entered unequivocally and cannot be considered as real, and especially as negative. This index for above referred media is not expedient

physics.optics↗
arXiv2014

Field emission in diode and triode vacuum nanostructures

The paper discusses the nano-diode and nano-triode structures of vacuum electronics. Such structures may have the dielectric film with the thickness of several nanometers wich is located on the cathode. Such film with a large dielectric constant reduces the thickness of the potential barrier by about film thickness and reduces the height of barrier. The grid electrode structure may contain several periods of metallization with a thickness of tens of nanometers, which allows one to obtain the resonant under barrier tunneling. For all structures we obtained electrostatic Green's function, the built profiles potential barriers, the calculated tunneling coefficients and Volt-Ampere Characteristics (VAC) with regard to the distribution of electron energies. The structures under consideration require to use of low voltages on the gate (grid) electrodes. They are promising for the electron gun with a large current controlled by low voltage on the grid, for example, in TWT with subsequent acceleration of the electron beam. Since a major influence on the tunneling provides the grid, the electrons emitted from the grid with approximately the Fermi velocity, and the calculation of the electron gun with multiple electrodes after the grid is greatly simplified.

cond-mat.other↗