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In this work, we report on the emergence of a photonic Hall effect (PHE) system within a narrow filtered background of a one-dimensional defective optical dielectric structure with graphene under the influence of a constant magnetic field regime. It is observed that at low temperature and relatively strong applied magnetic fields, electromagnetic defective transmission spectra corresponding to the two decoupled right- and left-handed polarized modes possess a step-like transmission feature which is referred to as “quantum Hall defect modes” (QHD modes or QHDs) in this paper. Tunable growing transitional transmission steps for QHDs with increasing magnetic field intensity were shown to be possible. Observation of sensitive magneto-transmission oscillations to the thermal excitations in the last plateaus slowly ascending toward unity is another special feature noted in this work. The results of this study, which is carried out based on rapid standard calculations for the transfer matrix approach is supplied with commercial simulations marking the first PHE system, promise an proper candidate for new photonic applications, especially new tunable magneto-based lenses and photonic magneto-thermal sensors. [ABSTRACT FROM AUTHOR]

To investigate the sensing properties of the Faraday effect in graphene in terahertz (THz), we consider the modulations of Dirac gaps in graphene when gas molecules are adsorbed to its surface. Here, the effect of the associated bandgap opening in graphene's spectrum on the sensing properties of the Faraday rotation (FR) in a 1D photonic graphene-based sensor with a microcavity defect channel covered by two graphene layers. Our proposed model introduces an optical contact-free mechanism for detecting low-concentration molecules attached to graphene's surface. We also show that FR angles could reveal reversal signs for a different amount of surface transfer doping. Finally, the effect of increasing the temperature on the Faraday effect at a certain opening gap in graphene's spectrum is investigated. Interestingly, stronger FR effect it was observed at higher temperatures. Our results could open the path for development of contact-free sensing applications in THz region. • Terahertz (THz) sensing of low-concentration molecules based on Faraday effect is introduced. • Effect of the energy bandgap of graphene on Faraday effect is investigated. • Faraday angle in a 1D photonic graphene-based sensor with a microcavity defect channel covered by two graphene layers is measured. [ABSTRACT FROM AUTHOR]

We investigate the effect of a perpendicular static magnetic field on the optical bandgap of a one-dimensional (1D) graphene-dielectric photonic crystal in order to examine the possibility of reaching a rich tunable photonic bandgap. The solution of the wave equation in the presence of the anisotropic Hall situation suggests two decoupled circularly polarized wave each exhibiting different degrees of bandgap tunability. It is also numerically demonstrated that applying different values of field intensity lead to perceptible changes in photonic bandgap of such a structure. Finally, the effect of opening a finite electronic gap in the spectrum of graphene on the optical dispersion solution of such a 1D photonic crystal is reported. It is shown that increasing the value of the electronic gap results in the shrinkage of the associated photonic bandgaps. [ABSTRACT FROM AUTHOR]

Terahertz (THz) anisotropic absorption in graphene could be significantly modified upon applying a static magnetic field on its ultra-fast 2D Dirac electrons. In general, by deriving the generalized Fresnel coefficients for monolayer graphene under applied magnetic field, relatively high anisotropic absorption for the incoming linearly polarized light with specific scattering angles could be achieved. We also prove that the light absorption of monolayer graphene corresponds well to its surface optical conductivity in the presence of a static magnetic field. Moreover, the temperature-dependent conductivity of graphene makes it possible to show that a step by step absorption feature would emerge at very low temperatures. We believe that these properties may be considered to be used in novel graphene-based THz application. • We introduced a general approach for calculating terahertz (THz) anisotropic absorption in graphene • Relatively high anisotropic absorption in graphene for incident linearly polarized light is achieved. • Light absorption of graphene corresponds well to peaks of the surface optical conductivity. [ABSTRACT FROM AUTHOR]

Strong Goos–Hänchen (GH) effect at a prism-graphene interface in the quantum Hall effect (QHE) condition is reported. Based on the full quantum description of the temperature-dependent surface conductivity of graphene present in the unconventional quantum Hall regime, magnetically strong tunable QHE GH shifts emerge. Our approach is based on deriving the generalized Fresnel coefficients with antisymmetric conductivity tensor for the Kerr phase of the incident linearly polarized light. Moreover, it is demonstrated that at low temperatures, GH shifts map plateaus as the intensity of the magnetic field grows. This quantum modulation of the GH effect in graphene by an applied magnetostatic bias may open doors to new opportunities for optical devices and QHE sensing applications in 2D materials. • Giant GH effect for a prism-graphene interface in QHE condition is revealed. • GH shifts are proved to be emerged as plateaus under QHE situation in graphene. • Adjustable model for GH shifts from different polarized reflected light is introduced. [ABSTRACT FROM AUTHOR]

The existence of a photonic bandgap in the visible range of light spectrum corresponding to a 1D graphene-based photonic crystal which recently has been proposed and is formed by embedding alternatively graphene layers into a dielectric background is investigated in this paper. By the use of the complete form of optical conductivity for the full expression of the tight-binding Hamiltonian of graphene layer, we numerically demonstrate an appeared bandgap in the visible region of the spectrum which can open up new route for further high-frequency applications of graphene-based photonic devices. It is revealed that the associated bandgap could be altered by changing the hopping energy and the amount of chemical potential leading to broadening the forbidden frequency regions with further increasing. Finally, it is also shown that the tunability feature of the photonic bandgap could be affected by changing the hopping energy. [ABSTRACT FROM AUTHOR]

Recently, huge attention has been drawn to improve optical sensing devices based on photonic resonators in the presence of graphene. In this paper, based on the transfer matrix approach and TE polarization of the incident electromagnetic waves, we numerically evaluate the transmission and reflection spectra for one-dimensional photonic resonators and surface plasmon resonances with strained graphene, respectively. We proved that a relatively small strain field in graphene can modulate linearly polarized resonant modes within the photonic bandgap of the defective crystal. Moreover, we study the strain effects on the surface plasmon resonances created by the evanescent wave technique at the interference between a monolayer graphene and prism. • We proved controlling the surface plasmon resonances in graphene by relatively small strain in kretschmann configuration for sensing applications. • We considered the effect of the chemical potential in a strained graphene on surface plasmon resonances. • We showed the modulation of defect modes by strain in a 1D graphene-based truncated PC. [ABSTRACT FROM AUTHOR]

Abstract: Polylactide (PLA) and PLA composites with void fractions as high as 65% were fabricated using low-pressure foam injection molding (FIM) and high-pressure FIM (HPFIM) equipped with mold opening and gas counter pressure. The cellular morphology and crystallinity were characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The mechanical (flexural and impact resistance) and thermal insulation properties were also measured. Unlike, talc, the addition of nanoclay markedly enhanced the ductility of solid PLA samples as well as significantly improved the cell morphology of foamed samples, which resulted in the increased specific modulus, strength and impact resistance. In all the PLA samples made using HPFIM, with an increased void fraction up to 55%, the flexural rigidity increased up to four times, the specific impact resistance increased up to 15%, and the thermal insulation increased up to three times. The results of this investigation revealed that low-density PLA composite foams with improved rigidity, impact strength, and thermal insulation can be developed using HPFIM for various applications such as transportation and construction industries. [Copyright &y& Elsevier]

Highlights: [•] A novel strategy was developed to produce cavity-integrated acoustic foams. [•] High open-cell contents are achieved with timely large mold opening. [•] Cell wall thinning and high shear rate resulted in desirable pin holes on the walls. [•] The cell morphology and acoustic behaviors were characterized. [•] Cavity-integrated acoustic foams presented remarkable acoustic properties. [ABSTRACT FROM AUTHOR]

Abstract: In this manuscript the effect of an opening gap on the dwell time corresponding to the electronic tunneling in graphene is explored. It is shown that tunneling time of quasiparticles in passing through junctions of gapped graphene as well as pure flakes is not independent of the barrier thickness and therefore Hartman effect is not observed due to tunneling of relativistic electrons with a finite effective mass in graphene. The numerical results also reveal that the traversal time in gapped graphene is equal to the traversal time in absence of the barrier for a broad range of incident energy. It is also found that the origin of the problem of Hartman effect could be explained in terms of an average-constant behavior of the probability density of the electronic wave under the barrier. [Copyright &y& Elsevier]

We examine the effect of a magnetic field that varies inversely as the square of distance on the Dirac fermion spectrum of graphene, a single layer of graphite. We find that unlike the case of the uniform magnetic field for which zero-energy modes exhibit half the degeneracy of the other levels in the energy spectrum, the ground state in this case, as well as the other energy levels, is doubly degenerate. We also get zero-energy solutions for the special case of ky = 0. [ABSTRACT FROM AUTHOR]

Abstract: For nano-electronics applications of graphene a mass gap in its energy spectrum is needed (like a conventional semiconductor). In this paper, motivated by mass production of graphene, by the use of 2D massive Dirac-like equation we obtain the exact solution for the transmission probability corresponding to the Klein tunneling of massive Dirac fermions through a two-dimensional barrier which can be considered as a n–p–n junction in a graphene nano-transistor, and show that contrary to the case of massless Dirac fermions which results in complete transparency of the barrier for normal incidence, the transmission probability, T, in this case, apart from some resonance conditions that lead to the total transparency of the barrier, is smaller than one and also depends on the band index. We then obtain the transmission through a potential barrier in which the massless electrons acquire a finite mass and find that the transmission, in this case, is independent of the band index and cannot reach unity. [Copyright &y& Elsevier]

• The existence of SPRs for graphene in the visible domain a 1D truncated PC was shown. • We demonstrated the effect of the chemical potential and hopping parameter on the dip modulations of SPRs. • We showed that the changes in the refractive index of the sensing medium affects SPRs in the visible domain. Visible surface plasmon resonances (SPRs) could be excited by TE wave polarization in one-dimensional photonic crystals (PCs) coated by a graphene layer under the Kretschmann configuration. In this work, the plasmonic Bloch wave properties beyond Dirac points in a one-dimensional graphene-based photonic sensing structure have been numerically studied. We demonstrate that emergent plasmonic dips in the reflectance spectra of the suggested photonic device in the visible region exhibit tunable characteristics upon modulation of the chemical potential and the hopping parameter. The sensitivity of the sensor in the visible domain has been numerically evaluated and also was compared with those considering the surface plasmon resonances in the terahertz regime. [ABSTRACT FROM AUTHOR]

Based on the transfer matrix method, we study a 1D defective photonic structure composed of periodical layers of Si and SiO 2 for which graphene with excited electronic states in a nonlinear regime is used as a covering layer of the middle silicone layer. We show that high transmission defective modes are derived in a relatively wide filtering range of visible frequencies. We also show that the position, height of defective modes are proved to be tunable with the width of each layer, hopping energy and the chemical potential. A significant result obtained in this research is the emergence of single defective modes in a relatively wide visible domain of light frequency. This structure with its reaction to the visible light beyond the linear response of graphene layers suggests optoelectronics communications in high-frequency applications. [ABSTRACT FROM AUTHOR]

We calculate the spectrum of massive Dirac fermions in graphene in the presence of an inhomogeneous magnetic field modeled by a step function. We find an analytical universal relation between the bandwidths and the propagating velocities of the modes at the border of the magnetic region, showing how, by tuning the mass term, one can control the speed of these traveling edge states. [ABSTRACT FROM AUTHOR]

The Goos–Hänchen-like (GHL) shift of Dirac fermions passing through a potential barrier for an anisotropic honeycomb lattice is studied. The analytical solution of the GHL shift and numerical results of the lateral shifts for three values of the merging parameter (δ) are presented. Then, the effects of the incidence angle and δ on the lateral shifts of anisotropic Dirac electrons are considered. Moreover, we investigate the influence of the uniaxial strain on a critical angle and see that it changes as a function of energy. We also demonstrate that by changing some parameters, more specifically merging parameter, one can obtain the different shifts for graphene under strong uniaxial strain. • Universal Hamiltonian for description deformation uniaxial strain on graphene used. • GHL shift of the transferred beam using the stationary phase method obtained. • The shift calculated for three value of δ which is an effective factor of our study. • We obtained the shifts with minus and plus sign for values of merging parameter. • By tuning various parameters such as δ and energy different shifts can be obtained. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) composite foams with two different void fractions of 30% and 55% were developed using regular foam injection molding (FIM) and FIM with mold opening, respectively. The microcellular structure and crystallization behavior were characterized using scanning electron microscopy and differential scanning calorimetry. The crystallization kinetics of the unfoamed samples was also analyzed with and without the presence of dissolved nitrogen (N 2 ). The results showed that the presence of nanoclay and talc, presence of pressurized N 2 , foaming action, and mold opening all enhanced the PLA’s crystallization kinetics during injection molding, leading to a threefold increase in the final crystallinity. Consequently, the presence of nanoclay/talc together with the expedited crystallization enhanced the PLA foams’ morphology with a finer and more uniform cell structure (cell size < 50 μm) at a void fraction of 55%. The mechanisms of the formation of such morphologies were also derived. [ABSTRACT FROM AUTHOR]

• We used the universal Hamiltonian for description of graphene under uniaxial strain. • The numerical results of the tunneling time for several values of δ were presented. • The effect of barrier's height, energy ... on the traversal time was considered. • The merging parameter was shown to be important character in the Hartman effect. • Hartman effect was not observed for δ = 0 and δ < 0 in the case of normal incidence. The dwell time corresponding to the Klein tunneling of Dirac fermions confined in single-layer graphene in the presence of uniaxial strain was investigated. The numerical results of the tunneling time and the transmission probability for several values of the merging parameter were presented. The effect of barrier's height/length, energy, incident angle and merging parameter on the traversal time was considered. Results showed that the merging parameter and the angle of the incidence were important characters in the existence of the Hartman effect, and therefore Hartman effect was not observed at tunneling of Dirac fermions with different values of merging parameter for δ = 0 and δ < 0 for normal incident. In the case of δ > 0 are equivalent to the gapped graphene under uniaxial strain at the merging point, tunneling time was independent on the barrier thickness. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Triassic Kangan Formation is composed of carbonate–evaporite sequences. [•] Various anhydrite structure and textures control reservoir quality carbonates. [•] Anhydrites are either intraformational seals or cements plugging pore spaces. [•] Relationships in facies associations/evaporite textures/sea-level fluctuation exist. [•] They show predictable patterns useful for sequence stratigraphic interpretations. [ABSTRACT FROM AUTHOR]

The presence of two defect layers in a one-dimensional photonic crystal which could be described numerically by the transfer matrix model becomes important when two defects modes might be controlled by the number of the middle layers. In this work, we compute the transmission spectra of a 1D photonic crystal with two graphene-based defect layers in the presence of an applied constant magnetic field. It is observed that an additional defect mode shows up at the lower edge of the photonic bandgap of the optical structure which could to be tuned by the Fermi energy, the intensity of the magnetic field and also the number of the layers between the defects. In addition, we investigated the effect of decreasing the number of middle layers on the transmission spectra of the photonic device. • We proved the existence of two defect modes with different properties. • We demonstrate that left and right handed defect modes exhibit a step-like transmission map. • We show that the middle layers between two defects affect the lower-edge defect modes. [ABSTRACT FROM AUTHOR]