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

The authors consider a model of charged semi-hard-core bosons on a square lattice with possible occupation number ({{n}_{i}} = 0,1,2~) at each site. Temperature phase diagrams of the model are obtained using quantum Monte Carlo calculations, and the effect of local charge correlations is studied. It is shown that local charge correlations increase the role of quantum fluctuations in the formation of phase states.

The structural perfection of a HgCdTe epitaxial layer with a minimum number of extended structural defects is ensured by the molecular beam epitaxy method and by the growth on substrates matched to the crystal lattice parameter. CdZnTe (211)B substrates (Orion Association, Moscow, Russia) have a total thickness variation (TTV) of less than 1.5 μm and a surface roughness of R_a = 0.45 nm (rms = 0.58 nm).

A series of experimental investigations was carried out to study the kinetics of spontaneous heterogeneous boiling-up of superheated n-pentane in two glass tubes. It was determined that the isobaric temperature dependences of the mean lifetime of the superheated liquid that were measured under similar conditions have threshold values in the temperature ranges of 100–115, 120–125, and 130–140°C.

The itinerant metamagnetic phase transition in metals within the Hubbard model for a face-centered cubic lattice was studied. The ratio of the transfer integrals between the nearest and next-to-nearest neighbors was chosen to provide a strong van Hove singularity in the density of electronic states. The magnetic field dependencies of magnetization in the transition region were obtained, and the effect of model parameters on the phenomenon under consideration was investigated.

Treatment with hydrostatic pressure of 10 MPa for 5 min stimulates the accelerated germination of lettuce seeds. Treatment with liquid oxygen has a depressing effect on seeds. In contrast, treatment of the same duration in liquid argon stimulates seed germination. The delay between seed treatment and germination has a negative impact on their sowing quality. Raising the temperature of seed storage enhances this effect.

Chiral thin film structures based on arrays of cobalt nanohelices obtained by oblique angle deposition were experimentally studied. It was shown that, in the conditions of electron-beam evaporation on rotating inclined substrate, arrays of nanohelices wound in the same direction are formed. By varying substrate rotation speed, it is possible to change geometrical sizes of those helixes (helix pitch, helix radius). The thus obtained chiral metasurface demonstrates pronounced asymmetry of optical characteristics at the reflection of right and left circular polarized light.

The self-diffusion coefficients for symmetrical tilt grain boundaries and for grain boundaries of the general type in nickel were calculated by atomistic simulation methods. The special tilt grain boundaries were simulated using a bicrystal model; and general-type grain boundaries, in a nanocrystal model. The self-diffusion coefficient was represented as a temperature dependence. The activation energies of self-diffusion were determined.

Quantum point contacts with a short (100-nm) channel in a high-mobility two-dimensional electron gas of GaAs/Al(Ga)As heterostructures and a short-channel p-type field-effect transistor in a silicon-on-insulator structure were fabricated and studied experimentally and by modeling at the Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia, in order to study the response of the samples to weak irradiation by an electromagnetic field with a frequency of ~2 GHz. This response in the tunneling mode at a temperature of 4.2 K turned out to be giant and was observed against the background of features caused by impurity disorder.

A brief overview is presented of results obtained at the Rzhanov Institute of Semiconductor Physics in the development of photon detectors and emitters promising for use in quantum cryptography systems, along with miniature quantum frequency standards based on the effect of coherent population trapping.

Spectra of deuterons and tritons are measured upon the absorption of stopped π⁻ mesons on a live target (an analog of a ²⁸Si target). It is shown this technique allows the identification of direct pathways for the formation of deuterons and tritons. The share of these particles in the total yields is ~30%.