Bulletin of the Russian Academy of Sciences: Physics最新文献

The ground and excited states of A- and B-excitons in monolayers of MoSe₂ and WSe₂ were studied by optical reflectance spectroscopy over a wide range of temperatures up to room temperature. It was shown that excited states are observed in the spectrum even at room temperature. Depending on the selected parameters of the heterostructure, the B-exciton line may be comparable in intensity to the A-exciton line.

The response time of a silicon-based plasmonic detector of electromagnetic radiation was investigated. For this purpose, frequency mixing experiments were carried out in the microwave frequency range. The sensitive element of the detector was embedded in the slots of a matched coplanar waveguide. The response time ({{tau }} = 60 pm 10) ps was estimated from the attenuation of the signal amplitude with increasing difference frequency.

Two-dimensional electron systems implemented in MgZnO/ZnO heterostructures with high interaction parameters were investigated. Inelastic light scattering study detected ferromagnetic transitions and spin textures. The dispersion dependences of key energy parameters were characterized.

Results are presented from in situ measurements of currents in the Chernaya Guba of Kandalaksha Bay, which is subject to tidal influence, in 2021–2023. Surface and bottom currents in different phases of the tidal cycle are measured using a grid of stations. The area in which the current from Nilmoguba was registered is determined, and in situ measurements are compared to results from modeling bottom currents.

Several versions of gold nanoparticles are proposed for detecting formazan formed by the enzymatic reduction of MTT reagent by E. coli enzymes. It is shown that gold nanostars coated with a micellar stabilizer are the most promising SERS substrates for detecting formazan in biological mixtures, reducing the required titer of bacteria by at least an order of magnitude.

Numerical modeling was made of planar resonators for the subterahertz frequency range, which are confined by various types of reflectors: Bragg mirrors, grating mirrors, and solid metal mirrors. The dependences of the enhancement of the electric field strength in the resonator on the structure parameters were constructed at normal incidence of an electromagnetic wave on the surface of the resonator. The physical limitations imposed on the enhancement were determined.

The luminescence of excitons and trions in a MoSe monolayer encapsulated with hBN under nonresonant photoexcitation of electron–hole pairs was studied as a function of temperature and pumping intensity. The shift of luminescence lines and the redistribution of intensities can be explained by the influence of both the Fermi gas of free electrons and localized states of electrons caused by the presence of impurities in boron nitride hBN.

The temporal dynamics of the photoreflectance signal was studied at a fractional filling factor of two-dimensional electrons of ν = 1/3 in a GaAs quantum well at liquid helium temperatures of T ∼ 0.6 K. It was demonstrated that, using a modified photon counting technique, it is possible to measure relaxation times of excitations in a Laughlin liquid of the order of 100 s.

An analysis is performed of the electromagnetic properties of a split-ring resonator based on a two-dimensional electron system (2DES). Studying the absorption of electromagnetic radiation by the 2DES in the geometry of a split-ring resonator reveals new plasma modes associated with a split in the structure. This plasmon resonance is observed under conditions of excitation by both alternating electric and alternating magnetic fields, allowing the possibility of developing highly efficient tunable phase elements.