Том 106, № 6 (2017)

We show that in contrast to the free electron model (standard BCS model), a particular gap in the spectrum of multiband superconductors opens at some distance from the Fermi energy, if conduction band is composed of hybridized atomic orbitals of different symmetries. This gap has composite superconducting-hybridization origin, because it exists only if both the superconductivity and the hybridization between different kinds of orbitals are present. Therefore, for many classes of superconductors with multiorbital structure such spectrum changes should take place. These particular changes in the spectrum at some distance from the Fermi level result in slow convergence of the spectral weight of the optical conductivity even in quite conventional superconductors with isotropic s-wave pairing mechanism.

The results of the experiment on the thermobaric annealing of titanium monoxide with a B1 cubic structure at a temperature of 2273 K have been analyzed. The analysis of these results has shown that an increase in the initial period of the lattice from 417.6 to 418.0 pm after processing at a pressure of 3 GPa and to 418.5 pm at a pressure of 6 GPa is due to the filling of vacant sites of the crystal structure with atoms. The ab initio quantum calculations indicate that the equilibrium period of the lattice should increase monotonically by 2% at a decrease in the concentration of vacancies from 16.7 to 0%. After aging the samples under normal conditions, the period of the lattice is no more than 421.0 pm and the concentration of vacancies is no lower than 11% because of the instability of the structure at lower concentrations of vacancies.

The assumption proposed in [U. Balucani et al., Phys. Rev. B 47, 3011 (1993)] that the space and time dependences of the characteristics of the microscopic structure and dynamics for the group of liquid alkali metals are reduced to a common general form through scaling transformations has been discussed. It has been found that such description is possible when scale units are (i) the effective size of a particle corresponding, in particular, to the experimentally measured position of the main peak in the static structure factor, (ii) the characteristic time scale of the thermal mean free path of the particle, and (iii) the parameters of the “liquid”–“crystal” phase separation (in particular, the melting temperature). This conclusion follows directly from the comparative analysis of experimental data on X-ray diffraction, as well as on the inelastic neutron and X-ray scattering data. This work develops the ideas proposed in [A. V. Mokshin et al., J. Chem. Phys. 121, 7341 (2004)].

Oblate nematic droplets encapsulated in a polymer specifying conical boundary conditions have been considered. Calculations by the extended Frank elastic continuum approach show that a number of various structures can be formed in such droplets under the variation of their size. Polarizing optical microscopy studies of composite film samples confirm the results of calculation and demonstrate the formation of the following orientational structures in the considered system: (i) a radial-bipolar structure with a twisted hedgehog defect and two hyperbolic boojums, (ii) an axial-bipolar structure with a circular disclination and two radial boojums, and (iii) a structure with a hedgehog defect, a hyperbolic boojum, and a radial boojum. Such a diversity of possible topologies of droplets is due to a complex balance between the energies of elasticity of the director field, disclinations, and anchoring with the surface, which is ensured by conical boundary conditions.

It has been shown with the use of the virial theorem and the equation of motion for the single-particle Green’s function that the thermodynamic properties of a single-component quantum gas beyond the perturbation theory are fully determined by the two-particle Green’s function Moscow Power Engineering Institute.

Chimera states consisting of synchronous and asynchronous domains in a medium of nonlinearly coupled phase oscillators have been considered. Stationary inhomogeneous solutions of the Ott–Antonsen equation for a complex order parameter that correspond to fundamental chimeras have been constructed. The direct numerical simulation has shown that these structures under certain conditions are transformed to oscillatory (breathing) chimera regimes because of the development of instability.

The influence of nonradiative damping of qubits on the microwave transport of photons propagating in a onedimensional microstrip line has been considered. Expressions for the transmission and reflection coefficients for two qubits have been obtained within the non-Hermitian Hamiltonian formalism. The indirect interaction between qubits caused by nonradiative decay into a common channel is explicitly taken into account in these expressions. It has been shown that this interaction leads to results significantly different from known results.

The current–voltage characteristics of Au/AAO(Au)/probe structures based on anodic aluminum oxide with pores incompletely filled with gold have been studied. It has been found that an electric field initiates the mass transfer of a rear Au electrode and the subsequent growth of the metal in unfilled parts of pores of the oxide matrix in the form of chains of gold islands. It has been established that this transfer, which appears at a positive potential of the probe, is due primarily to the effect of electron drag of the metal (Au). Estimates have been obtained for the effective radius of Au islands (2 nm), the width of a gap between islands (0.5 nm), the height of potential barriers (100 meV), and the characteristic resistance of tunnel junctions (30 kΩ ~ h/e²), which is typical of point quantum contacts. The structures demonstrate reversible resistive switching between low- (~1 MΩ) and high-resistance (>100 GΩ) states.