Surface waves in a magnetized ferrite slab filled with a wire medium

International audienceNovel metamaterial, based on wire medium embedded into magnetized ferrite, is studied. Waves in unbounded ferrites filled with wire media, surface wave at the interface of this metamaterial and the air as well as waves in a ferrite slab adjacent to a wire medium are considered. Different geometries of wires arrangement and different magnetization directions are discussed. Effective permeability was introduced for the case where both plasma and magnetic properties take place. Dispersion diagrams and applicability of the Drude model for the description of the wire medium in a host matrix, possessing high permittivity and permeability, are discussed

Nonlinear-optical Negative-index Metamaterials: Extraordinary Properties and Applications

The principles of nanoengineering of metamaterials which support optical electromagnetic and elastic waves with negative group velocity are described. Extraordinary properties of nonlinear-optical energy transfer between contra-propagating short pulses of electromagnetic and elastic waves are investigated and prospective unique photonic devices are discussed. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3538

The Theory of Brown Dwarfs and Extrasolar Giant Planets

Straddling the traditional realms of the planets and the stars, objects below the edge of the main sequence have such unique properties, and are being discovered in such quantities, that one can rightly claim that a new field at the interface of planetary science and and astronomy is being born. In this review, we explore the essential elements of the theory of brown dwarfs and giant planets, as well as of the new spectroscopic classes L and T. To this end, we describe their evolution, spectra, atmospheric compositions, chemistry, physics, and nuclear phases and explain the basic systematics of substellar-mass objects across three orders of magnitude in both mass and age and a factor of 30 in effective temperature. Moreover, we discuss the distinctive features of those extrasolar giant planets that are irradiated by a central primary, in particular their reflection spectra, albedos, and transits. Aspects of the latest theory of Jupiter and Saturn are also presented. Throughout, we highlight the effects of condensates, clouds, molecular abundances, and molecular/atomic opacities in brown dwarf and giant planet atmospheres and summarize the resulting spectral diagnostics. Where possible, the theory is put in its current observational context.Comment: 67 pages (including 36 figures), RMP RevTeX LaTeX, accepted for publication in the Reviews of Modern Physics. 30 figures are color. Most of the figures are in GIF format to reduce the overall size. The full version with figures can also be found at: http://jupiter.as.arizona.edu/~burrows/papers/rm

Author Correction: Casimir forces exerted by epsilon-near-zero hyperbolic materials (Scientific Reports, (2020), 10, 1, (16831), 10.1038/s41598-020-73995-0)

In the original version of this Article, Igor S. Nefedov was incorrectly affiliated with “Saratov State University, Astrakhanskaya 83, Saratov, Russian Federation, 410012”. The correct affiliation is listed below: Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya St., Moscow 117198, Russia. This error has now been corrected in the HTML and PDF versions of the Article. © 2020, The Author(s)

Enhancement of circular dichroism in epsilon-near-zero chiral hyperbolic metamaterials

We are presenting a theoretical study of light transmission through a slab of hyperbolic metamaterial composed of gold rods, with chiral inclusions, thus possessing both hyperbolic and chiral properties. 4 × 4 transfer matrix formalism was used for solution of a wave transmission through a slab of a chiral hyperbolic material. We have shown that circular dichroism (CD) can be enhanced by several orders of magnitude in epsilon-near-zero (ENZ) mode when the diagonal component of the permittivity tensor corresponding to the normal to interface coordinate tends to zero. The necessary condition of the enhancement is a non-zero light incidence angle. This effect results from a considerable wavelength shortening in normal direction that increases the interaction between light and matter. We have shown that the increase of the incidence angle leads to the increase of dichroism in vicinity of ENZ wavelength range and the dichroism can change sign in this resonance area. The dichroism becomes huge at large incidence angles (θ > 30°) and for each incidence angle the maximal enhancement is observed within a certain wavelength range (in vicinity of-near-zero). In opposite to discussion of the enhancement of the pseudochirality reported previously in the literature, our study relates to the true chirality. We expect these results to be of interest to researchers engaged in chemical composition of organic substances by retrieval of effective parameters from measurements of the CD. © 2019 IOP Publishing Ltd

A theory for terahertz lasers based on a graphene hyperbolic metamaterial

We present a theory for terahertz (THz) wave emission in a cavity containing a graphene-based asymmetric hyperbolic metamaterial (AHMM), and the results of the calculation of the output power of the THz laser. An asymmetry appears in the spatial spectrum of the eigenmodes due to a tilt of an anisotropy axis with respect to the interfaces of the AHMM that results in a difference in the wave vector components for waves propagating in opposite directions. This AHMM is an active medium in the THz region due to an inverted population of charge carriers in graphene. The theory is based on the analysis of eigenwaves in the cavity containing the graphene-based AHMM and the use of the transfer matrix method. The components of the Poynting vector, normal to the interface of the AHMM, have been calculated for different eigenmodes, taking into account the gain saturation. The gain saturation manifests itself as a decrease of the negative imaginary part of the effective permittivity of the metamaterial. This gain saturation results from the dependence of the chemical potential in graphene on the component of the electric field transverse to the graphene sheets. Here, the balance of gain versus loss predicts the intensity of the AHMM THz laser emission. © 2020 IOP Publishing Ltd

Controlling the electronic properties of a nanoporous carbon surface by modifying the pores with alkali metal atoms

We investigate a process of controlling the electronic properties of a surface of nanoporous carbon glass-like thin films when the surface pores are filled with potassium atoms. The presence of impurities on the surface in the form of chemically adsorbed hydrogen and oxygen atoms, and also in the form of hydroxyl (OH) groups, is taken into account. It is found that even in the presence of impurities, the work function of a carbon nanoporous glass-like film can be reduced by several tenths of an electron volt when the nanopores are filled with potassium atoms. At the same time, almost all potassium atoms are ionized, losing one electron, which passes to the carbon framework of the film. This is due to the nanosizes of the pores in which the electron clouds of the potassium atom interact maximally with the electrons of the carbon framework. As a result, this leads to an improvement in the electrical conductivity and an increase in the electron density at the Fermi level. Thus, we conclude that an increase in the number of nanosized pores on the film surface makes it possible to effectively modify it, providing an effective control of the electronic structure and emission properties. © 2020 by the authors

Effective-medium model of wire metamaterials in the problems of radiative heat transfer

Peer reviewe

Electrical and photovoltaic properties of layered composite films of covalently bonded graphene and single-walled carbon nanotubes

In this paper, we present the results of a computational study of the electrical and photovoltaic properties of a perspective composite material; that is, layered composite films of covalently bonded graphene and single-walled carbon nanotubes (SWCNTs). The purpose of the study is to identify the topological patterns in controlling the electrical and photovoltaic properties of mono-and bilayer graphene/CNT composite films with a covalent bonding of a nanotube and graphene sheet, using in silico methods. This in silico study was carried out for the super-cells of mono-and bilayer graphene/CNT composite films with the CNTs (10,0) and (12,0) at distances between the nanotubes of 10 and 12 hexagons. This found that the type of conductivity of the nanotubes does not fundamentally affect the patterns of current flow in the graphene/CNT composite films. This control of the diameter of the nanotubes and the distance between them allows us to control the profile of the absorption spectrum of the electromagnetic waves in the range of 20-2000 nm. The control of the distance between the SWCNTs allows one to control the absorption intensity without a significant peak shift. This revealed that there is no obvious dependence of the integrated photocurrent on the distance between the nanotubes, and the photocurrent varies between 3%-4%. © 2020 by the authors