Vol 108, No 7 (2018)

We have calculated partial contributions of different atomic subshells to the total dipole sum rule in the random phase approximation with exchange and found that they are essentially different from the numbers of electrons in respective subshells. This difference manifests the strength of the intershell interaction, due to which some partial contributions are much larger while the other are considerably smaller than the numbers of electrons in the respective shells. Particularly impressive is the growth of contribution of the outer among f and d subshells while all other are usually losers, the largest of which are the s-subshells. Concrete calculations done for Ar, Pd, Xe, and Ra atoms. Comparison with existing experimental data is uninformative since to obtain the absolute values of the cross sections one usually normalizes them, assuming that the dipole partial sum rule is valid with reasonable accuracy.

We analyzed the influence of applied bias changing and external magnetic field switching on the non-stationary spin-polarized currents behavior in the correlated single-level quantum dot coupled to the non-magnetic leads. It was demonstrated that spin polarization and direction of the non-stationary currents could be changed to the opposite ones by applied bias voltage. The degree of the currents spin polarization changes the sign following the applied bias polarity. The possibility of spin-polarized train pulses generation with the opposite degree of polarization was revealed. Moreover, the presence of external magnetic field allows considering correlated single-level quantum dot as an effective non-stationary spin filter.

The specific heat of Ho_0.01Lu_0.99B₁₂ single crystals with dynamic charge stripes is studied at low and ultralow temperatures (0.07–20 K) in applied magnetic fields of 0–9 Т. It is shown that additional contributions to the specific heat appear at magnetic fields exceeding 1 T. These contributions depend on the orientation of the magnetic field and can be as large as 15% of the specific heat related to the subsystem of holmium ions in the cubic crystal field.

The effect of microwave radiation on the amplitudes of the quantum magnetocapacitance oscillations in field-effect transistors has been studied. It has been found that the microwave-induced variation of the oscillation amplitude depends nonmonotonically on the magnetic field including the amplitude enhancement effect. It has been shown that this behavior is due to the band bending near the edge of the gate. The effect has been attributed to the interference of quantum oscillations with radiation-induced magneto-oscillations of the screening length of a static electric field.

Titanium monoxide with the basis crystal structure B1 is of interest because of an anomalously high concentration of vacancies and diverse effects of atom–vacancy ordering. It was previously believed that the application of relatively low pressures to such systems does not change the crystal structure type, and the crystal structure is densified through a decrease in the equilibrium concentration of defects. The genetic algorithm to search for optimal structures and calculations by the electron density functional method have demonstrated that phases with a structure derivative of the B1 structure should be metastable in a wide pressure range from 0 to 100 GPa. Two defectless hexagonal modifications—the ε-TiO and H-TiO phases—are thermodynamically stable at P < 28 GPa and P > 28 GPa, respectively. These phases demonstrate a pronounced pseudogap at the Fermi level and, thereby, have a low electrical conductivity.

The formation of a jet and a frozen microstructure after the subnanosecond laser irradiation of a thick film from the side of a transparent substrate has been explained in numerical simulation. Such simulations were previously performed only for the irradiation of a thin film by an ultrashort pulse. The results obtained in this work also allow the description of physical effects at the ablation of a metal into a liquid in the theoretically unstudied case of a subnanosecond pulse of great applied interest. Dielectric Material.

The microwave absorption spectra of a two-dimensional electron system based on GaAs/AlGaAs heterostructures in a perpendicular magnetic field are experimentally investigated. A unique noninvasive technique for the excitation of “dark” axisymmetric plasma oscillations in single disks of two-dimensional electrons is developed. The excitation conditions and physical properties of the new dark plasma modes are studied in detail. The experimental results are in excellent agreement with theoretical calculations.