arXiv subjects

N. E. Firsova

Publications and source records attributed to N. E. Firsova.

11 recordsLinked to original sources

arXiv2019

Complex conductivity of monolayer graphene and Zitterbewegung

A recently derived formula for complex conductivity of the monolayer graphene is analyzed. We show that the real and imaginary parts in this formula obey the Kramers and Kronig dispersion relations which are a good test for validity of the formula for complex conductivity of monolayer graphene. We consider also an additional test for this formula, sensitive to the integral characteristic of the conductance such as the famous f sum rule. We write it in the two dimensional form and show that it fulfils identically if we admit the cyclotron mass as an effective one and take the principal value of the integral. We find a deep relation between the graphene complex optical conductivity singularities and electrons Zitterbewegung in graphene. Namely, the value of Zitterbewegung frequency is related with the recently found magnitudes of the inductance L and capacitance C by the Thomson formula.

cond-mat.mtrl-sci↗

arXiv2017

On corrected formula for graphene quantum conductivity

Graphene membrane irradiated by weak activating periodic electric field in terahertz range is considered. The corrected formula for the graphene quantum conductivity is found. The obtained formula gives complex conjugate results when radiation polarization direction is clockwise or it is opposite clockwise. The found formula allows us to see that the graphene membrane is an oscillating contour. Its eigen frequency coincides with a singularity point of the conductivity and depends on the electrons concentration. So the graphene membrane could be used as an antenna or a transistor and its eigen frequency could be tuned by doping in a large terahertz-infrared frequency range. The obtained formula allows us also to calculate the graphene membrane quantum inductivity and capacitance. The found dependence on electrons concentration is consistent with experiments. The method of the proof is based on the study of the time-dependent density matrix. The exact solution of the von Neumann equation for density matrix is found for our case in linear approximation on the external field. On this basis the induced current is studied and then the formula for quantum conductivity as a function of external field frequency and temperature is obtained. The method of the proof suggested in this paper could be used to study other problems. The found formula for quantum conductivity can be used to correct the SPPs Dispersion Relation and for the description of radiation process. It would be useful to take the obtained results into account when constructing devices containing graphene membrane nanoantenna. Such project could make it possible to create wireless communications among nanosystems. This would be promising research area of energy harvesting applications.

cond-mat.mes-hall↗

arXiv2015

Nanoantenna properties of graphene membrane. Quantum theory

The graphene membrane irradiated by weak activating alternative electric field in terahertz range was considered. The quantum approach based on the time-dependent density matrix method was used. The exact solution was obtained for graphene membrane density matrix equation in linear on the external field approximation. The graphene electromagnetic response was studied i.e. the formulae for the induced current and conductivity were found and analyzed neglecting loss. The obtained formula for the conductivity showed that the graphene membrane was an oscillating contour and its fundamental eigen frequency coincided with a singularity point of the conductivity. This formula allowed us to calculate the graphene membrane inductivity and the capacitance. So the graphene membrane could be used as an antenna or a transistor. It was shown that its eigen frequency could be tuned by doping as its value was found to depend on electrons concentration. It was obtained that the eigen frequency could be tuned in a rather large frequency range 1-100 terahertz as electrons concentration in graphene may differ considerably. The found dependence on concentration correlates with experiments. It would be useful to take the obtained results into account when constructing devices containing graphene membrane nanoantenna allowing wireless communications among nanosystems. This could be promising research area of energy harvesting applications.

cond-mat.mes-hall↗

arXiv2014

Radiative decay effects influence the local electromagnetic response of the monolayer graphene with surface corrugations in terahertz range

We continue the study of surface corrugations influence on the monolayer graphene local electromagnetic response in terahertz range we started earlier. The effects of radiative decay, double-valley structure of charge carriers spectrum in graphene and the breathing surface curvature form induced synthetic electric fields are taken into account. To fulfill this program the generalized nonlinear self-consistent equation is obtained. In case of weak external alternating electric field for the obtained equation in linear approximation on the external electric field the exact solution is found. It shows that in this case we get local dephasing in induced current paths depending on the surface form . This theoretical result qualitatively explains the corresponding experiments with local current patterns in graphene without using fully quantum approach which is necessary for theoretical description of such phenomenon in graphene nanoribbons. Besides the formulae obtained in the present paper could become the basis of the new method of the imaging of surface corrugations form for given picture of local current paths. The obtained results allow to study mechanical behavior of materials at nanoscale deviates from macroscoping established concepts and this is of particular importance for graphene.

cond-mat.mes-hall↗

arXiv2014

Surface corrugations influence on monolayer graphene electromagnetic response

We consider the corrugated monolayer graphene membrane electromagnetic (from both valleys) response in terahertz range. We study the generated in irradiated graphene total current for the first time taking into account both the synthetic electric fields arising due to the (inevitable) presence in graphene of inherent out-of-plane nanodeformations and the double-valleys energy spectrum of Dirac charge particles. Our approach is based on atomistic quantum mechanics used for the description of valence $π-σ$ bonds changes generated by activating external periodic electric field and also for mechanism of Dirac electron interaction with this time-dependent perturbation. We consider the problem in the framework of the model of noninteracting Dirac electrons. Assuming surface corrugations not to be very rough we obtain for weak fields the formula for the total current induced in graphene membrane. Our formula describes the curved current lines in the linear in $E^{ext}(t)$ approximation for the given graphene surface form. We show that the local direction of current lines is determined by synthetic electric field whose direction may essentially differ from the one of the external field and depends on the local curvature of the graphene membrane. We also demonstrate that valley currents generated by the external field have nonzero elliptic polarization angles depending on the point (x,y). Valley currents are shown to rotate in opposite directions in different valleys. The results obtained below can be applied to the analysis of different devices in terahertz optics and optoelectronics and the imaging experiments at the Dirac point.

cond-mat.mes-hall↗

arXiv2010

Classical model of confinement

The confinement mechanism proposed earlier and then applied successfully to meson spectroscopy by one of the authors is interpreted in classical terms. For this aim the unique solution of the Maxwell equations, an analog of the corresponding unique solution of the SU(3)-Yang-Mills equations describing linear confinement in quantum chromodynamics, is used. Motion of a charged particle is studied in the field representing magnetic part of the mentioned solution and it is shown that one deals with the full classical confinement of the charged particle in such a field: under any initial conditions the particle motion is accomplished within a finite region of space so that the particle trajectory is near magnetic field lines while the latter are compact manifolds (circles). An asymptotical expansion for the trajectory form in the strong field limit is adduced. The possible application of the obtained results in thermonuclear plasma physics is also shortly outlined.

hep-th↗

arXiv2005

Increase of the electron-positron Hawking radiation from Schwarzschild black holes by Dirac monopoles

An algorithm for numerical computation of the barrier transparency for the potentials surrounding Schwarzschild black holes is described for massive spinor particles. It is then applied to calculate the total (including electronic neutrino and the contributions of twisted field configurations connected with Dirac monopoles) luminosity for the electron-positron Hawking radiation from a Schwarzschild black hole with mass $M=10^{15}$ g. It is found that the contribution due to monopoles can be of order 12% of the total electron-positron luminosity.

astro-ph↗

arXiv2003

S-matrices for spinor particles on Reissner-Nordström black holes

The scattering problems arising when considering the contribution of the topologically inequivalent configurations of the spinors on Reissner-Nordström black holes to the Hawking radiation are correctly stated. The corresponding $S$-matrices are described and presented in the form convenient to numerical computations.

gr-qc↗

arXiv2003

Increase of the Hawking radiation for spinor particles from Schwarzschild black holes by Dirac monopoles

An algorithm for numerical computation of the barrier transparency for the potentials surrounding Schwarzschild black holes is described for massless spinor particles. It is then applied to calculate the all configurations (including the contributions of twisted field configurations connected with Dirac monopoles) luminosity for the Hawking radiation from a Schwarzschild black hole. It is found that the contribution due to monopoles can be of order 22 % of the all configurations luminosity.

astro-ph↗

arXiv2000

Increase of the pion-kaon Hawking radiation from Schwarzschild black holes by Dirac monopoles

An algorithm for numerical computation of the barrier transparency for the potentials surrounding Schwarzschild black holes is described for massive scalar particles. It is then applied to calculate the total (including all particle species and the contributions of twisted field configurations connected with Dirac monopoles) luminosity for the pion-kaon Hawking radiation from a Schwarzschild black hole with mass $M=10^{12}$ g. It is found that the contribution due to monopoles can be of order 11% of the total pion-kaon luminosity.

astro-ph↗

arXiv1997

Correct statement of a scattering problem for quantum charged scalar particles on the Reissner-Nordström black holes

We study a correct statement of the scattering problem arising for quantum charged scalar particles on the Reissner-Nordström black holes when taking into account the own electric field of black hole. The elements of the corresponding S-matrix are explored in the form convenient to physical applications and for applying numerical methods. Some further possible issues are outlined.

gr-qc↗