Новые публикации

Orbital rotation of spheroidal Mie particles driven by counter-propagating circularly-polarized beams

Bulgakov, E.N., Ershov, A.E., Kimberg, V., Gerasimov, V.S., Maksimov, D.N.// Optics Express//

We theoretically consider orbital rotation of a spheroidal submicron particle in the field of two counter-propagating circularly polarized Gaussian beams. We derived equations connecting the parameters of the circular orbits centered on the beams axis to the optical force and torque. The equations show that, besides orbital rotation, the spheroidal particle simultaneously rotates around its equatorial axis. We found that two distinct dynamic regimes are possible. The orbital motion can be accompanied by a rapid proper rotation with angular velocity an order of magnitude larger than the angular velocity of the orbital rotation. Alternatively, the orbital and proper rotations can be synchronized. The direction of orbital rotation can either coincide with or be opposite to the direction of rotation of the electric vector. The findings are confirmed by direct numerical simulations. The results can be of use in development of nano-scale gyroscopes as well in shape-selective sorting of submicron particles.

Electro-optical properties of cholesteric with tangential-conical anchoring at oblique light incidence

Kostikov, D.A., Krakhalev, M.N., Nabol, S.V., (...), Timofeev, I.V., Zyryanov, V.Y.A.// Optics Express//

https://doi.org/10.1364/OE.582556

The effects of the incidence angle and applied voltage on the polarization state of light passing through a cholesteric (CLC) with tangential-conical boundary conditions are investigated. Both cases in which the CLC director on the input substrate is perpendicular or parallel to the light incidence plane are considered. The polarization azimuth following mode is characterized as a function of the incidence angle and voltage. The wavelength-independent mode of change in light polarization has been discovered. The influence of the helix pitch and CLC layer thickness on the realized modes parameters is in good agreement with theoretical predictions based on the Frank-Oseen approach.

Achieving high-performance near-infrared Cr3+-activated phosphor via A&C lattice sites cosubstitution strategy in garnet for plant lighting

Peng, C., Tang, B., Zhang, X., (...), Zhang, H., Lei, B.// Science China Materials//

https://doi.org/10.1007/s40843-025-3691-9

Near-infrared (NIR) spectroscopy has significantly advanced NIR light sources. However, creating NIR emitters with optimal luminescence properties, high thermal stability, and adjustable emission peaks poses a critical challenge for future smart NIR devices. We introduced a chemical unit cosubstitution strategy by incorporating Ca²⁺ and Sn⁴⁺ ions into the garnet structure. Through this approach, Y_3−yCa_yGa_4.95−ySn_yG₁₂:0.05Cr³⁺ (y = 0–1) phosphors were developed by modulating the A&C ligands, resulting in emission centers ranging from 708 to 768 nm. The modified local environment of Cr³⁺ accounts for the increased light intensity (2.71 times) and broadening observed. Furthermore, this study investigated the impact of varying Cr³⁺ concentrations (Y_2.6Ca_0.4Ga_4.6−xSn_0.4G₁₂:xCr³⁺) on the production of high-performance phosphors. Compared with Y₃Ga_4.93G₁₂:0.07Cr³⁺, the optimized phosphor exhibited exceptional external quantum efficiency (EQE = 34.96%). The luminescence enhancement is attributed to an increase in radiative transitions caused by octahedral Jahn-Teller distortion, whereas the notable thermal stability (91.3% at 423 K) is attributed to the presence of weak electron-phonon coupling (EPC) and oxygen vacancy (O_V) defects. Finally, by combining it with a 450 nm blue LED chip, we constructed a near-infrared phosphor-converted LED (NIR pc-LED) device with superior electroluminescence efficiency (18.8% @ 100 mA), increasing the ultralow quenching rate (< 5% intensity loss after 30 days of operation) and demonstrating remarkable performance in plant lighting applications.

Two-terminal transport in biased lattices

Kolovsky, A.R.// Physical Review B//

DOI: https://doi.org/10.1103/6grr-dkry

We analyze the quantum transport of charged fermionic particles in the tight-binding lattice connecting two particle reservoirs (leads). If the lead chemical potentials are different they create an electric field which tilts the lattice. We study the effect of this tilt on quantum transport in the presence of weak decoherence processes in the lattice. It is shown that a Landauer ballistic transport regime for a small tilt changes to a diffusive Esaki-Tsu transport regime for a larger tilt. The critical tilt for this crossover is determined by the condition that the Wannier-Stark localization length coincides with the length of the lattice.

Synthesis, characterization and electrochemical properties of Pd,PdO/Ni@C nanoparticles as an anode in acidic direct methanol fuel cells

Churilov, G., Isakova, V., Vnukova, N., (...), Glushenko, G., Tomashevich, Y.// Fullerenes Nanotubes and Carbon Nanostructures//

https://doi.org/10.1080/1536383X.2025.2595222

Nickel nanoparticles encapsulated in a continuous carbon shell (Ni@C) were synthesized in a helium arc-discharge plasma, purified by acid treatment, and subsequently decorated with palladium via the thermal decomposition of palladium acetylacetonate, as confirmed by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The reaction of methanol oxidation in an acidic medium was investigated using cyclic voltammetry on the composite (Pd,PdO/Ni@C) applied to a graphite electrode. It was demonstrated that the composite possesses electrochemical activity and can be used as an anode in acidic direct methanol fuel cells.