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Tarkhanyan R.H.,Institute of Electronic Structure and Laser FORTH | Tarkhanyan R.H.,Armenian Institute of Radiophysics and Electronics | Niarchos D.G.,Greek National Center For Scientific Research
Physica Status Solidi (B) Basic Research | Year: 2011

A new class of nonradiative surface electromagnetic waves guided by the interface between two enantiomorph uniaxially bianisotropic media is predicted. The waves are caused by bianisotropy and are absent in the case of enantiomorph bi-isotropic materials. The basic properties of the waves, in particular, dispersion relation and localization conditions differ dramatically from those for conventional surface waves propagating along the interface between chiral and achiral media, as well as between two different achiral media. These waves can be considered as a generalization of Dyakonov-type surface waves in the case of enantiomeric bianisotropic media. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gevorkian Zh.S.,Armenian Institute of Radiophysics and Electronics | Gevorkian Zh.S.,Yerevan Physics Institute
Physical Review Special Topics - Accelerators and Beams | Year: 2010

Radiation of a charged particle moving parallel to an inhomogeneous surface is considered. Within a single formalism periodic and random gratings are examined. For the periodically inhomogeneous surface we derive new expressions for the dispersion relation and the spectral-angular intensity. In particular, for a given observation direction two wavelengths are emitted instead of one wavelength of the standard Smith-Purcell effect. For a rough surface we show that the main contribution to the radiation intensity is given by surface polaritons induced on the interface between two media. These polaritons are multiply scattered on the roughness of the surface and convert into real photons. The spectral-angular intensity is calculated and its dependence on different parameters is revealed. © 2010 The American Physical Society.

Gevorkian Z.,Yerevan Physics Institute | Gevorkian Z.,Armenian Institute of Radiophysics and Electronics | Gasparian V.,California State University, Bakersfield | Lozovik Y.,Russian Academy of Sciences
Applied Physics Letters | Year: 2016

Solar cells based on organometal halide perovskites have recently become very promising among other materials because of their cost-effective character and improvements in efficiency. Such performance is primarily associated with effective light absorption and large diffusion length of charge carriers. Our paper is devoted to the explanation of large diffusion lengths in these systems. The transport mean free path of charged carriers in a perovskite/TiO2 heterojunction that is an important constituent of the solar cells have been analyzed. Large transport length is explained by the planar diffusion of indirect excitons. Diffusion length of the coupled system increases by several orders compared to single carrier length due to the correlated character of the effective field acting on the exciton. © 2016 AIP Publishing LLC.

Nersisyan H.B.,Friedrich - Alexander - University, Erlangen - Nuremberg | Nersisyan H.B.,Armenian Institute of Radiophysics and Electronics | Zwicknagel G.,Friedrich - Alexander - University, Erlangen - Nuremberg
Physics of Plasmas | Year: 2010

Binary collisions of the gyrating charged particles in an external magnetic field are considered within a classical second-order perturbation theory, i.e., up to contributions that are quadratic in the binary interaction, starting from the unperturbed helical motion of the particles. The calculations are done with the help of a binary collision treatment, which is valid for any strength of the magnetic field and involves all harmonics of the particles' cyclotron motion. The energy transfer is explicitly calculated for a regularized and screened potential, which is both of finite range and nonsingular at the origin. The validity of the perturbation treatment is evaluated by comparing with classical trajectory Monte Carlo (CTMC) calculations which also allow one to investigate the strong collisions with large energy and velocity transfer at low velocities. For large initial velocities, on the other hand, only small velocity transfers occur. There the nonperturbative numerical CTMC results agree excellently with the predictions of the perturbative treatment. © 2010 American Institute of Physics.

Gevorkian Z.,Yerevan Physics Institute | Gevorkian Z.,Armenian Institute of Radiophysics and Electronics | Gasparian V.,California State University, Bakersfield
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We have analyzed analytically the Faraday rotation of an electromagnetic wave for a magnetoactive thin metallic film with a nanostructured surface profile. Periodic as well as random surface profiles were considered. The plasmon contribution to the Faraday angle was studied. For the periodic grating case, we have shown that the maximum rotation angle is achieved when the surface plasmon wave number coincides with one of the wave numbers of the inverse lattice. Enhancement of the Faraday angle at plasmonic band edges is predicted. In the case of a random surface profile, it is shown that the diffusion of surface magnetoplasmons gives a dominant contribution to the Faraday rotation. Comparison with experiments is carried out. © 2014 American Physical Society.

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