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A. V. Chaplik

Publications and source records attributed to A. V. Chaplik.

11 recordsLinked to original sources
arXiv2026

Acoustic Plasmon Resonance: Breaking the Anderson Stiffness Paradigm in Quasi-Two-Dimensional Superconducting Films

Recent experiments on superconducting films have revealed an acoustic plasmon mode that depends critically on the superconducting transition, directly challenging the long-standing Anderson-Higgs paradigm regarding the stiffness of the plasma spectrum in superconductors. In this Letter, we provide a microscopic theoretical framework that explains this behavior and establishes the physical conditions under which classical Anderson-Higgs constraints are bypassed. We demonstrate that in films of finite thickness, the transverse redistribution of normal and superfluid charge densities enables a unique coupling mechanism to electromagnetic radiation - a feature fundamentally absent in the conventional Carlson-Goldman scenario. Our theory predicts an acoustic mode whose dispersion, temperature scaling, and dependence on film thickness are in remarkable agreement with recent experimental observations. By delineating the regime of this acoustic response, we reconcile the observed electromagnetic activity of collective excitations with the fundamental principles of superconductivity.

cond-mat.supr-con↗
arXiv2021

Size and Shape Effects in the Orbital Magnetization of TMDs Monolayers

The intrinsic orbital magnetization of a TMD monolayer is usually calculated for a plane unbounded system without mentioning the geometrical shape of samples and boundary conditions (BCs) for electron wave functions. The method of calculations includes allowing for the Berry curvature contribution also in the case when the system is described by the two-band minimal model [9]. In the present paper, we show that the geometrical and topological properties of the specimen, as well as the BCs, play an important role in the problem of magnetization even for a macroscopic specimen.

cond-mat.mes-hall↗
arXiv2021

Quantum Dot in a Hybrid Structure with Dipolar Excitons

Electron states in a quantum dot (QD) located near a 2D system of dipolar excitons are perturbed by fluctuations of the exciton density caused by the electron-exciton interaction. This results in the frequency changes of electron transitions in a QD. The frequency depends on the exciton density, as well as on the exciton gas phase state. In the present work, the shifts of the two lowest QD energy levels are found both in the normal state of the exciton system and for the Bose-Einstein condensation (BEC) regime.

cond-mat.mes-hall↗
arXiv2019

Bound electron pair in a MOS-structure

In developing our previous contribution (arXiv:1804.00889) we have numerically found the bound state energy and correspondent wave function of the two electrons confined to move in a quantum well placed close to the gate electrode. Spin-orbit interaction (SOI) and image charge forces result in effective attraction between electrons. We considered also the effect of gate voltage applied to the structure and discovered that this can essentially increase the bound energy of the pair so that it remains stable even at room temperature.

cond-mat.mes-hall↗
arXiv2018

Formation of the Bielectron in a 2D System due to Spin-Orbit Interaction and Image Forces

It is shown that two electrons located in a quantum well near a metal electrode attract each other due to the spin-orbit interaction (SOI) of the Bychkov-Rashba type and the electrostatic image forces. Using the example of a simple model, it is shown that, with quite attainable values of the characteristic parameters of the system, the effective attraction caused by SOI prevails over the Coulomb repulsion, and the formation of a bielectron becomes possible.

cond-mat.mes-hall↗
arXiv2013

Impurity Screening and Surface Acoustic Wave Absorption in a Dipolar Exciton Condensate at Finite Temperatures

We describe the behavior of a repulsively interacting Bose-Einstein condensate of indirect dipolar exciton gas in a double quantum well (QW) system under external static or dynamic electric fields at finite temperatures. Electrostatic perturbation is considered to be created by an impurity atom or shot-range defect of QW fluctuation. The screening of this defect potential by an exciton condensate is studied. We find asymptotic spatial dependence of the screened potential and analyse its dependence on the temperature and exciton concentration. It is shown that the asymptotic of the screened potential has a steep power law dependence in contrast to the well known results of electron gas. This peculiarity reflects the bosonic nature of the exciton condensate. The behavior of exciton condensate under external alternative field created by a surface acoustic wave (SAW) is examined in detail. We focus our attention on the dependence of SAW absorption coefficient on temperature and exciton concentration. We found that at zero temperatures Landau damping does not contribute to the SAW absorption, but the Belyaev mechanism produces unusual behavior of SAW absorption coefficient on exciton concentration: if the exciton concentration exceeds some critical value, the SAW absorption vanishes. At finite temperatures Landau damping comes into action and results in washing out the sharp absorption behavior. Such unusual SAW absorption properties can be used for experimental evidence of the exciton condensation. This method is also applicable to the experimental testing of both dark and bright exciton condensates, that is impossible to do with the optical luminescence technique.

cond-mat.mes-hall↗
arXiv2007

Friedel oscillations of screening in nanotubes

In 3D and 2D electronic systems the singular contribution to the static permittivity $ε$ (Kohn singularity) is a small correction to the regular part of $ε$ but it results in the leading term in asymptotic behavior of the screened potential (Friedel oscillations). In the present letter we show that for nanotubes quite different results are valid: $ε$ becomes infinitely large at the singular point and the Friedel oscillations do not play the dominant role in the screening at the large distances. Moreover, the zero and highest cylindrical harmonics of the effective potential are screened by quite different mechanisms.

cond-mat.other↗
arXiv2006

Spatially inhomogeneous states of charge carrier in graphene

We study an interaction of 2D quasiparticles with linear dispersion (graphene) with impurity potentials. It is shown that in 1D potential well (quantum wire) there are discrete levels, corresponding to localized states, whereas in 2D well (quantum dot) there are no such states. Scattering cross-section of electrons (holes) of graphene by an axially symmetric potential well is found and it is shown that for infinetily large energy of incoming particles the cross-section tends to a constant. The effective Hamiltonian for a curved quantum wire of graphene is derived and it is shown that the corresponding geometric potential cannot form 1D bound states.

cond-mat.mes-hall↗
arXiv2005

Bound states in a 2D short range potential induced by spin-orbit interaction

We have discovered an unexpected and surprising fact: a 2D axially symmetric short-range potential contains {\it infinite} number of the levels of negative energy {\it if one takes into account the spin-orbit (SO) interaction.} For a shallow well ($m_eU_0R^2/\hbar^2 \ll 1$, where $m_e$ is the effective mass, $U_0$ and $R$ are the depth and the radius of the well, correspondingly) and weak SO coupling ($|α|m_eR/\hbar \ll 1$, $α$ is the SO coupling constant) exactly one two-fold degenerate bound state exists for each value of the half-integer moment $j=m+1/2$, and the corresponding binding energy $E_m$ extremely rapidly decreases with increasing $m$.

cond-mat.mes-hall↗