Vol 104, No 5 (2016)

We study the transport of strongly interacting electrons on the surface of liquid helium confined in a microchannel geometry, near the current threshold point. The current threshold depends on the electrostatic confinement, created by the microchannel electrodes, and on the electrostatic potential of electron system. Depending on the geometry of the microchannel, the current pinch-off can occur at the center or move to the edges of the microchannel, as confirmed by Finite Element Model calculations. The confining potential dependence of electron conductivity above the current threshold point is consistent with a classical charge continuum model. However, we find that below the threshold point electron transport is suppressed due to charging energy effects.

According to experimental data on X-ray scattering and reflectometry with synchrotron radiation, a twodimensional crystallization phase transition in a monolayer of melissic acid at the n-hexane–water interface with a decrease in the temperature occurs after a wetting transition.

The structural, electron, phonon, and other characteristics of the metallic normal phase of hydrogen at a pressure of 500 GPa are calculated by an ab initio mathematical simulation. It is shown that metallic hydrogen having a lattice with the I41/amd symmetry is a stable phase at a high hydrostatic compression pressure. The resulting structure has the spectrum of phonons stable with respect to the decay.

Resonance magnetic tunneling in heterostructures formed by graphene single sheets separated by a hexagonal boron nitride barrier and two gates has been investigated. The design has allowed studying transitions between individual Landau levels of different graphene sheets bounded by a narrow conductivity window with a width controlled by a bias voltage. Three-dimensional plots of the equilibrium tunneling conductivity against both gate voltages reflecting the displacement of resonances between various combinations of the individual Landau levels in the top and bottom sheets have been drawn and identified. The discovered step structure of the current patterns with plateaus and abrupt jumps between them is caused by pinning of chemical potentials to the Landau levels in two graphene sheets. The presence of negative differential conductivity regions in the current–voltage characteristics in the magnetic field with the peak-to-valley current ratio I_p/I_v ~ 2 indicates a high degree of the conservation of an in-plane momentum component at tunneling.

Experimental data on inelastic ⁹Be+α scattering induced by 90-MeV α particles are analyzed. The 2.78-MeV excited state is shown to have spin–parity of I^π=1/2^- in agreement with the existing data. For the 4.70-MeV excited state, it is impossible to make an unambiguous choice between the previous value I^π = 3/2⁺, and the proposed new value I^π = 1/2⁻.

A new effect has been experimentally revealed: a sequence of flashes of a two-component laser plasma creates a flow containing torsional Alfvén and slow magnetoacoustic waves in a magnetic flux tube.

Key generation in a two-pass quantum cryptography system involving protocols on geometrically uniform coherent states is studied. Results on the correction of errors in this system without opening a part of the raw key to estimate the probability of errors but involving the monitoring of the parameters of the system and the quantum communication channel sufficient for an a priori estimate of the probability of errors, which is used to choose a correcting code, are reported.

Isotopically pure ¹²С and ^13С diamonds are synthesized by chemical vapor deposition and impulsive stimulated Raman scattering in these crystals is investigated. The thermal conductivity of ¹²С isotopically pure damond and ^natC diamond with natural isotopic composition is measured. Phonon-nondegenerate Stokes lasing based on the χ⁽³⁾ nonlinearity in the ¹²С, ¹³С, and ^natC diamond “triad” is attained, which opens a new stage in the development of diamond photonics.

Resonance relaxation displacements of dislocations in NaCl crystals placed in crossed static and alternating ultralow magnetic fields in the electron paramagnetic resonance scheme are discussed. The Earth’s magnetic field B_Earth ≈ 50μT and other fields in the range of 26–261 μT are used as the static field. New strongly anisotropic properties of the effect have been revealed. Frequency spectra including numerous peaks of paths at low pump frequencies beginning with 10 kHz, as well as the quartet of equidistant peaks at high frequencies (~1.4 MHz at B=B_Earth), have been measured. The effect is also observed in the pulsed pump field with a resonance duration of ~0.5 μs. Resonance changes have been detected in the microhardness of ZnO, triglycine sulfate, and potassium hydrogen phthalate crystals after their exposure in the Earth’s magnetic field in the same electron paramagnetic resonance scheme.