Том 103, № 1 (2016)

A method is developed to consider the particle–phonon coupling (PC) effects in the problem of finding odd–even double mass differences (DMD) of magic nuclei within the approach starting from the free NN potential. Three PC effects are taken into account, the phonon induced interaction, the renormalization of the “ends” due to the Z-factors and the change of the single-particle energies. We use the perturbation theory in g_L², where g_L is the vertex of the L-phonon creation. PC corrections to single-particle energies are found selfconsistently. In addition to the usual pole diagram, the phonon “tadpole” diagram is taken into account approximately. Results for double-magic ¹³²Sn and ²⁰⁸Pb nuclei show that the PC corrections make agreement with the experimental data better.

Variations of the rigidity spectrum and anisotropy of cosmic rays in the period of the ground-level enhancement (GLE) of cosmic rays on November 6, 1997, according to the data from the worldwide network of ground-based stations and satellites have been studied by the unique spectrographic global survey method developed at the Institute of Solar–Terrestrial Physics, Siberian Branch, Russian Academy of Sciences. Rigidity spectra of cosmic rays in various periods of the event under study have been determined. It has been shown that the acceleration of protons in the period of this GLE event was observed to a rigidity of ~10–12 GV, and neither a power-law nor an exponential function of the rigidity of particles describes the differential rigidity spectra of cosmic rays in the event under consideration. The analysis has indicated that the Earth at the time of the GLE event was in a looplike structure of the interplanetary magnetic field.

It has been shown that the resonance interaction of particles with an electromagnetic wave in optically thin ensembles of particles with a permanent dipole moment generates low-frequency (terahertz or subterahertz) radiation with the carrier frequency equal to the frequency of nutation oscillations of the exciting wave.

A time-reversal invariant topological superconductivity is suggested to be realized in a quasi-one-dimensional structure on a plane, which is fabricated by filling the superconducting materials into the periodic channel of dielectric matrices like zeolite and asbestos under high pressure. The topological superconducting phase sets up in the presence of large spin–orbit interactions when intra-wire s-wave and inter-wire d-wave pairings take place. Kramers pairs of Majorana bound states emerge at the edges of each wire. We analyze effects of the Zeeman magnetic field on Majorana zero-energy states. In-plane magnetic field was shown to make asymmetric the energy dispersion, nevertheless Majorana fermions survive due to protection of a particle–hole symmetry. Tunneling of Majorana quasiparticle from the end of one wire to the nearest-neighboring one yields edge fractional Josephson current with 4π-periodicity.

We analyze measurements of the magnetization, differential susceptibility and specific heat of quasi-onedimensional insulator Cu(C₄H₄N₂)(NO₃)₂ (CuPzN) subjected to magnetic fields. We show that the thermodynamic properties are defined by quantum spin liquid formed with spinons, with the magnetic field tuning the insulator CuPzN towards quantum critical point related to fermion condensation quantum phase transition (FCQPT) at which the spinon effective mass diverges kinematically. We show that the FCQPT concept permits to reveal and explain the scaling behavior of thermodynamic characteristics. For the first time, we construct the schematic T–H (temperature-magnetic field) phase diagram of CuPzN that contains Landau–Fermi-liquid, crossover and non-Fermi liquid parts, thus resembling that of heavy-fermion compounds.

The anisotropic characteristics of an iron silicide (Fe₃Si) epitaxial thin magnetic film grown on a Si(111) silicon vicinal surface with a misorientation angle of 0.14° have been measured by the ferromagnetic resonance method. It has been shown that the polar and azimuth misorientation angles of the crystallographic plane of the substrate can be determined simultaneously from the angular dependences of the ferromagnetic resonance field of the epitaxial film. The effective saturation magnetization of the film M_eff = 1105 G and the constant of the cubic magnetocrystalline anisotropy K₄ = 1.15 × 10⁵ erg/cm³ have been determined. The misorientation of the substrate plane leads to the formation of steps on the film surface and, as a result, to the appearance of uniaxial magnetic anisotropy of the magnetic dipole nature with the constant K₂ = 796 erg/cm³. Small unidirectional magnetic anisotropy (K₁ = 163 erg/cm³), which may be associated with symmetry breaking on the steps of the film and is due to the Dzyaloshinskii–Moriya interaction, has been detected.

A physical mechanism of the implementation of undamped Rabi oscillations in the system of exciton polaritons in a semiconductor microcavity in the presence of nonresonant pumping has been proposed. Various mechanisms of the stimulated scattering of excitons from the reservoir have been considered. It has been shown that undamped oscillations of the population of the photon component of the condensate can be caused by the feeding of a coherent Rabi oscillator owing to the pair scattering of excitons from the reservoir to the ground state. The effect should be observed in spite of a more intense relaxation of polaritons of the upper branch observed experimentally.

The analytical theory of Bose–Einstein condensation of an ideal gas in mesoscopic systems has been briefly reviewed in application to traps with arbitrary shapes and dimension. This theory describes the phases of the classical gas and the formed Bose–Einstein condensate, as well as the entire vicinity of the phase transition point. The statistics and thermodynamics of Bose–Einstein condensation have been studied in detail, including their self-similar structure in the critical region, transition to the thermodynamic limit, effect of boundary conditions on the properties of a system, and nonequivalence of the description of Bose–Einstein condensation in different statistical ensembles. The complete classification of universality classes of Bose–Einstein condensation has been given.