Tailorable epsilon-negative and epsilon-near-zero behavior of TiC/CCTO metacomposites: Low-frequency plasma oscillation

Epsilon-negative ([Formula: see text]) and epsilon-near-zero (ENZ) property was demonstrated in titanium carbide/copper calcium titanate (TiC/CCTO) metacomposites. Benefiting from the moderate concentration of free electrons in TiC filler and its adjustable three-dimensional (3D) networks, weakly negative permittivity ([Formula: see text]200 at 20 MHz) was achieved. Not only that, tailoring the negative permittivity of metacomposites from [Formula: see text]200 to [Formula: see text]2060, [Formula: see text]4200, [Formula: see text]14000 and [Formula: see text]70000 at 20 MHz was realized by simply increasing TiC content. Besides, Drude model was used to explain the radio-frequency (RF) negative permittivity and quantified the collective plasma oscillation in TiC networks.

Determination of the parameters of coherent magneto-optical layers on a finite absorbing substrate from thermal radiation spectra

A possibility of determining the parameters of a coherent magneto-optical layer on a finite incoherent absorbing substrate by analyzing the spectra of its thermal radiation (TR) has been investigated. On the example of a plane-parallel InAs semiconductor plate silver-coated on the back surface, it has been shown that a complex analysis of TR spectra, both without and with the presence of magnetic field, makes it possible to determine the thickness, optical, magneto-optical and electric parameters of the layer. Algorithms for the calculation and analysis of TR spectra are adduced, which simplify determination of layer parameters and increase the accuracy of results. Comparing the position of the extremes of the experimental zero-field spectrum with the theoretical calculations, the thickness of the sample and the plasma oscillation frequency in the used semiconductor have been determined. The analysis of the relative contrast of interference oscillations in the TR spectrum in the magnetic field using previously defined parameters enabled to ascertain the spectral dependence of the Faraday rotation angle and to determine the concentration, effective mass and type of current carriers. It has been assumed, that such analysis of luminescence spectra also allows determining the parameters of magneto-optical layers and structures.

Tailorable negative permittivity in Fe/BaTiO3 meta-composites

Meta-composites with negative permittivity are promising candidates for future electronics such as microwave absorbers, novel capacitors, etc. In this work, we proposed to develop the Fe/BaTiO3 meta-composites with tuneable negative permittivity. Fe content influenced the conductivity of composites and even led to the change of the conductive mechanism. The tuneable permittivity behavior was achieved by controlling the Fe fraction, and the plasma oscillation theory was employed to explain the negative permittivity behavior. Meanwhile, a frequency-switched negative permittivity was observed in this composite, which could be used to extend applications of meta-composites.

Epitaxial Growth of Bendable Cubic NiO and In2O3 Thin Films on Synthetic Mica for p- and n-type Wide-Bandgap Semiconductor Oxides

Bendable p-type NiO and n-type In2O3 thin films were epitaxially grown on synthetic mica using mist chemical vapor deposition. It was found that at a growth temperature of 400 °C, epitaxially grown cubic (111) NiO thin films developed twin rotational domains, and the epitaxial relationship between each domain and the substrate was (111) NiO [1-10] or [10-1] || (001) synthetic mica [100]. In the visible light region, the epitaxial NiO thin films showed high transparencies, and their cut-offs appeared in the UV region. Additionally, at a growth temperature of 500 °C, cubic (111) In2O3 thin films with and without Sn doping were epitaxially grown on synthetic mica. As a result of the plasma oscillation of free carriers, Sn-doped In2O3 thin films exhibited reflection characteristics in the infrared region, while maintaining their visible light transmission characteristics. Furthermore, compared with non-doped In2O3, Sn doping decreased the sheet resistance by two digits.

Transient setting of relativistic ponderomotive non-linearity and filamentation of ultra-short laser pulses in collisionless plasmas

We study the setting up of relativistic ponderomotive non-linearity in an under-dense collisionless cold plasma. Using the fluid model, coupled system of equations of the laser beam and electron plasma oscillations has been derived. We present the numerical simulation for this coupled system of equations, when the coupling arises through relativistic ponderomotive non-linearity. The filamentation of the laser beam has been found to vary appreciably with perturbation wave number. The results show that with time, localized structures become more complex and the plasma oscillation frequency spectra have several harmonic peaks at terahertz frequencies when the electron plasma frequency is in terahertz range and laser frequency is around 2.35 × 1015 rad/s. We also present the semi-analytical model to capture the underlying physics.

Effect of dust particle and magnetic field on EEPF and plasma oscillation

The significance of dust particles for the electron energy probability function (EEPF) and plasma oscillations is studied under varying magnetic field strength in a filamentary discharge hydrogen plasma. The experimental result shows that with an increase in dust density, the electron density decreases as a result of the charging of dust grains in the plasma background. A bi-Maxwellian EEPF is computed in both a pristine hydrogen plasma and a dust-containing plasma at different magnetic field strengths. We have observed that the increase in magnetic field decreases the lower energy electron population. The electron population of the lower energy range shows nearly identical results at magnetic field, $B\leqslant 3.7$ mT whereas the behaviour of the high-energy electron population becomes identical for a field strength $B\leqslant 5.8$ mT. From the observation, we have seen that the mid energy electron population slightly decreases and the high energy electron population slightly increases due to the presence of dust particles as compared to a pristine plasma. Further, very low energy electron population remains almost unchanged. With increase in dust density, the mid energy electron population further decreases whereas the high energy electron population slightly increases for different magnetic fields. But, no changes were observed for the very low energy electron population in the presence of dust particles. From the study of plasma oscillation, it is observed that the dominant frequency associated with the plasma oscillation is matched with the ion cyclotron frequency. The amplitude of the ion cyclotron frequency reduces with the increase of dust density which might be due to the decrease of plasma density.

Emergence of Network Bifurcation Triggered by Entanglement

In many non-linear systems, such as plasma oscillation, boson condensation, chemical reaction, and even predatory-prey oscillation, the coarse-grained dynamics are governed by an equation containing anti-symmetric transitions, known as the anti-symmetric Lotka-Volterra (ALV) equations. In this work, we prove the existence of a novel bifurcation mechanism for the ALV equations, where the equilibrium state can be drastically changed by flipping the stability of a pair of fixed points. As an application, we focus on the implications of the bifurcation mechanism for evolutionary networks; we found that the bifurcation point can be determined quantitatively by the microscopic quantum entanglement. The equilibrium state can be critically changed from one type of global demographic condensation to another state that supports global cooperation for homogeneous networks. In other words, our results indicate that there exist a class of many-body systems where the macroscopic properties are invariant with a certain amount of microscopic entanglement, but they can be changed abruptly once the entanglement exceeds a critical value. Furthermore, we provide numerical evidence showing that the emergence of bifurcation is robust against the change of the network topologies, and the critical values are in good agreement with our theoretical prediction. These results show that the bifurcation mechanism could be ubiquitous in many physical systems, in addition to evolutionary networks.