Архив научных статейиз журнала «Письма в "Журнал экспериментальной и теоретической физики"»
ONE-DIMENSIONAL STRONGLY INTERACTING ELECTRONS WITH SINGLE IMPURITY: CONDUCTANCE REEMERGENCE
AFONIN V.V., PETROV V.YU. — 2015 г.
We show that conductance of ID channel with one point-like impurity critically depends on asymptotic behavior of e-e interaction at small momenta k (about inverse length of a channel). Conductance reemerges (contrary to the case of point-like repulsive potential) if potential V (k = 0) = 0. For example, this happens if the bare e-e interaction is screened by the charges in the bulk. The relation of this phenomena to the long-range order present in the Luttinger model is discussed. We consider spinless electrons but generalization is straightforward.
OPTICAL STORAGE BASED ON COUPLING OF ONE-WAY EDGE MODES AND CAVITY MODES
FANG Y., HE H.Q., JIANG T., NI ZH. — 2015 г.
We design a new kind of optical storage composed of a ring resonator that is based on both the one-way property of the edge modes of magneto-optical photonic crystals and the coupling effect of cavities. The ring resonator can be served as an optical storage through a close field circulation. Through another edge waveguide and coupling cavity, the electromagnetic signals can be either written into the storage or be taken out from it.
ORIGIN OF NONLINEAR CONTRIBUTION TO THE SHIFT OF THE CRITICAL TEMPERATURE IN ATOMIC BOSE-EINSTEIN CONDENSATES
BRISCESE F., DE LLANO M., GRETHER M., SERGEENKOV S. — 2015 г.
We discuss a possible origin of the experimentally observed nonlinear contribution to the shift Δ T c = T c - T 0 c of the critical temperature T c in an atomic Bose-Einstein condensate (BEC) with respect to the critical temperature T 0 c of an ideal gas. We found that accounting for a nonlinear (quadratic) Zeeman effect (with applied magnetic field closely matching a Feshbach resonance field B0) in the mean-field approximation results in a rather significant enormalization of the field-free nonlinear contribution b2, namely ΔT c/T 0 c ≃ b∗ 2(a/λ T ) 2 (where a is the s-wave scattering length, λ T is the thermal wavelength at T 0 c ) with b∗ 2 = ϒ 2b 2 and γ = γ(B 0). In particular, we predict b ∗ 2 ≃ 42.3 for the B 0 ≃ 403G resonance observed in the 39K BEC.
OSCILLATIONS OF MAGNETORESISTANCE IN A CLEAN HOLLOW CYLINDER WITH FLUCTUATING RADIUS
IOSELEVICB A.S. — 2015 г.
We consider magnetic oscillations of resistivity of a clean (mean free path t ˃ R) hollow cylinder with fluctuating (with an amplitude of fluctuations Δ R< R) radius R, threaded by magnetic flux Ф. We demonstrate, that for weak fluctuations (Δ R F -1) the oscillations have a standard period 2Ф о, characteristic for oscillations in a clean system, while for Δ R F -1 they become Ф о-periodic, which was expected only for dirty systems with t о-periodic magnetic oscillations in very clean Bismuth wires.
PROFILE OF COHERENT VORTICES IN TWO-DIMENSIONAL TURBULENCE
KOLOKOLOV I.V., LEBEDEV V.V. — 2015 г.
The inverse cascade of two-dimensional turbulence in a restricted domain leads to creating a coherent flow containing a number of system-size vortices. We examine the case of forcing turbulence with zero bottom friction where the final statistically steady state is determined by viscosity. We analytically establish structure of the coherent vortices in the state.
PROPERTIES OF ELECTRONS SCATTERED BY A STRONG PLANE ELECTROMAGNETIC WAVE WITH A LINEAR POLARIZATION: SEMICLASSICAL TREATMENT
BOGDANOV O.V., KAZINSKI P.O. — 2015 г.
The problem of scattering of ultrarelativistic electrons by a strong plane electromagnetic wave of a low (optical) frequency and linear polarization is solved in the semiclassical approximation, when the electron wave packet size is much smaller than the wavelength of electromagnetic wave. The exit momenta of ultrarelativistic electrons scattered are found using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum components of electrons traversed the electromagnetic wave depend weakly on the initial values of momenta. These electrons are mostly scattered at small angles to the propagation direction of the electromagnetic wave. The maximum Lorentz factor of electrons crossed the electromagnetic wave is proportional to the work done by the electromagnetic field and is independent of the initial momentum. The momentum component parallel to the electric field vector of the electromagnetic wave is determined solely by the laser beam diameter measured in the units of the classical electron radius. As for the reflected electrons, they for the most part lose the energy, but remain relativistic. A reflection law that relates the incident and reflection angles and is independent of any parameters is found.
QUANTUM AUTO-IONIZATION OF MOLECULAR EXCITONS AND PHOTOVOLTAIC CONVERSION
BENDERSKII V.A., KATS E.I. — 2015 г.
This paper explores a novel way of charge separation (auto-ionization) of molecular excitons, by quantum tunneling through nano-size p-n junction. This mechanism can dominate the standard one (i.e., when Frenkel exciton is ionized at donor or acceptor impurity sites) for very short, nano-size, p-n junction, where the junction electric field can be strong for relatively small (on the order of 1 V) voltage drop. Within a simple one-dimensional model for the depletion region of the p-n junction (donor and acceptor reservoirs connected by a short molecular wire) we compute the quantum yield Yb for the tunneling exciton auto-ionization in the “bulk” of the depletion region. For modern organic photo-sensitive materials with p-n junction size on the order of 10-20 nm, Yb could be close to 1. Such a high efficiency of the charge separation (one of the main factor entering figure of merit, indicating how good are photovoltaic conversion cells) makes this new mechanism potentially very perspective for the applications.
RADIATIVE PARTON ENERGY LOSS IN EXPANDING QUARK-GLUON PLASMA WITH MAGNETIC MONOPOLES
ZAKHAROV B.G. — 2015 г.
We study radiative parton energy loss in an expanding quark-gluon plasma with magnetic monopoles. We find that for realistic number density of thermal monopoles obtained in lattice simulations parton rescatterings on monopoles can considerably enhance energy loss for plasma produced in AA collisions at RHIC and LHC energies. However, contrary to previous expectations, monopoles do not lead to the surface dominance of energy loss.
RECOVERING OF SUPERCONDUCTIVITY IN S/F BILAYERS UNDER SPIN-DEPENDENT NONEQUILIBRIUM QUASIPARTICLE DISTRIBUTION
BOBKOV A.M., BOBKOV I.V. — 2015 г.
We study theoretically the influence of spin accumulation on superconductivity in a superconductor/ferromagnet bilayer. It is well-known that the superconductivity in Superconductor/Ferromagnet (S/F) bilayers is suppressed by the proximity to a ferromagnet. The spin accumulation by itself is also a depairing factor. But here we show that creation of the spin accumulation on top of effective exchange depairing, caused by the proximity to a ferromagnet, can lead to an opposite result. The superconductivity can be partially recovered by spin-dependent quasiparticle distribution. The systems with realistic parameters are considered and the possible experimental setup is proposed.
RELAXATION TIME MAPPING OF SINGLE QUANTUM DOTS AND SUBSTRATE BACKGROUND FLUORESCENCE
CHIPOULINE A., FASOLD S., GEISS R., GRANGE R., MUKHINX, PERTSCH T., PSHENAY-SEVERIN E., STEINBRCK A. — 2015 г.
We experimentally investigated the role of background signal in time resolved photoluminescence experiments with single quantum dots on substrates. We show that the background fluorescence signal from thin gold films fabricated by electron-beam evaporation and from AI2O3 layers fabricated by atomic layer deposition have to be taken into consideration in experiments on the single photon level. Though all investigated components can be distinguished by their photoluminescence decay rates, the presence of the background signal prevents the observation of photon anti-bunching from single quantum dots. Moreover, a single quantum dot acts as a hot-spot enabling the plasmon supported fluorescence enhancement of gold.
SENSITIVITY OF BAIKAL-GVD NEUTRINO TELESCOPE TO NEUTRINO EMISSION TOWARD THE CENTER OF GALACTIC DARK MATTER HALO
AVRORIN A.D., AVRORIN A.V., AYNUTDINOV V.M., BANNASCH R., BELOLAPTIKOV I.A., BOGORODSKY D. YU., BRUDANIN V.B., BUDNEV N.M., DANILCHENKO I.A., DEMIDOV S.V., DOMOGATSKY G.V., DOROSHENKO A.A., DYACHOK A.N., DZHILKIBAEV ZH.-A. M., FIALKOVSKY S.V., GAFAROV A.R., GAPONENKO O.N., GOLUBKOV K.V., GRESS T.I., HONZ Z., KEBKAL K.G., KEBKAL O.G., KONISCHEV K.V., KONSTANTINOV E.N., KOROBCHENKO A.V., KOSHECHKINA A.P., KOSHEL F.K., KOZHIN A.V., KULEPOV V.F., KULESHOV D.A., LJASHUK V.I., MILENIN M.B., MIRGAZOV R.A., OSIPOVA E.R., PANFILOV A.I., PAN’KOV L.V., PEREVALOV A.A., PLISKOVSKY E.N., RJABOV E.V., ROZANOV M.I., RUBTZOV V. YU., SHAYBONOV B.A., SHEIFIER A.A., SKURIHIN A.V., SMAGINA A.A., SUVOROVA O.V., TARASBANSKY B.A., YAKOVLEV S.A., ZAGORODNIKOV A.V., ZHUKOVA V.A., ZURBANOV Y.L. — 2015 г.
We analyse sensitivity of the gigaton volume telescope Baikal-GVD for detection of neutrino signal from dark matter annihilations or decays in the Galactic Center. Expected bounds on dark matter annihilation cross section and its lifetime are found for several annihilation/decay channels.
SHOT NOISE OF THE EDGE TRANSPORT IN THE INVERTED BAND HGTE QUANTUM WELLS
DVORETSKY S.A., KHRAPAI V.S., KVON Z.D., MIKHAILOV N.N., SHOVKUN D.V., TIKHONOV E.S. — 2015 г.
We investigate the current noise in HgTe-based quantum wells with an inverted band structure in the regime of disordered edge transport. Consistent with previous experiments, the edge resistance strongly exceeds h/e 2 and weakly depends on the temperature. The shot noise is well below the Poissonian value and characterized by the Fano factor with gate voltage and sample to sample variations in the range 0.1 < F < 0.3. Given the fact that our devices are shorter than the most pessimistic estimate of the ballistic dephasing length, these observations exclude the possibility of one-dimensional helical edge transport. Instead, we suggest that a disordered multi-mode conduction is responsible for the edge transport in our experiment.
STRENGTH OF SOLID AND MOLTEN ALUMINUM UNDER DYNAMIC TENSION
MAYER A.E., MAYER P.N. — 2015 г.
Under dynamic loading, an aluminum melt has a comparable or even higher strength than solid aluminum at room temperature. This phenomenon is possible due to the uniformity of the melt and the homogeneous nucleation of voids within it, whereas the fracture mechanics of a solid are controlled by pre-existing defects. High-current electron irradiation of an initially solid metal plate can be used to observe this effect.
STRONG COUPLING CONSTANT FROM QCD ANALYSIS OF THE FIXED-TARGET DIS DATA
KOTIKOV A.V., KRIVOKHIZHIN V.G., SHAIKHATDENOV B.G. — 2015 г.
Deep inelastic scattering data on F2 structure function obtained in fixed-target experiments were analyzed in the valence quark approximation with a next-to-next-to-leading-order accuracy. The strong coupling constant is found to be α s(M 2 Z ) = 0.1157 ± 0.0022 (total exp.error), which is seen to be well compatible with the average world value. This study is meant to at least partially explain differences in the predictions for observables at the LHC found recently, caused by usage of various sets of parton distribution functions obtained by different groups.
SURFACE 2π-WALLS IN POLAR FREE-STANDING SMECTIC FILMS
DOLGANOV P.V., DOLGANOV V.K., FUKUDA A. — 2015 г.
It was found that electric field in free-standing smectic films at high temperature leads to formation of unusual 2 π-walls, with quite different structure from the structure of classical 2π-walls. The walls are formed by the change of molecular orientation not only along the film plane (as in usual walls) but also in smectic layers between two surfaces of the film. These walls are nuclei of surface field-induced synclinic-anticlinic transition between states with transverse and longitudinal electric polarization.
SURFACE PHOTOCURRENT IN ELECTRON GAS OVER LIQUID HE SUBJECT TO QUANTIZING MAGNETIC FIELD
ENTIN M.V., MAGARILL L.I. — 2015 г.
The photogalvanic effect is studied in electron gas over the liquid He surface with the presence of quantizing magnetic field. The gas is affected by the weak alternating microwave electric field tilted towards the surface normal. Both linear and circular photogalvanic effects are studied. The current occurs via indirect phototransition with the participation of ripplons emission or absorption. The photogalvanic tensor has strong resonances at the microwave frequency со approaching to the frequencies of transitions between size-quantized subbands. The resonances are symmetric or antisymmetric, depending on a tensor component. Other resonances appear at ω ≈ nω c, where n being integer and ω c is the cyclotron frequency. It is found that the latter resonances split to two peaks connected with emission or absorption of ripplons. The calculated photogalvanic coefficients are in accord with the experimental observed values.
SYSTEM OF NEUTRON MICROBEAMS FROM A PLANAR WAVEGUIDE
IGNATOVICH V.K., KOZHEVNIKOV S.V., NIKITENKO YU. V., OTT F., PETRENKO A.V. — 2015 г.
Results of experimental investigations of space, angular and wavelength distribution in neutron microbeams obtained for the first time with the help of a resonant planar neutron waveguide at the time-of-flight reflectometer of the IBR-2 pulsed reactor are reported and comparison with theoretical calculations is presented. Possible application of microbeams in physical experiments is discussed.
TEMPERATURE DERIVATIVE OF THE CHEMICAL POTENTIAL AND ITS MAGNETOOSCILLATIONS IN TWO-DIMENSIONAL SYSTEM
BURMISTROV I.S., KUNTSEVICH A.YU., PUDALOV V.M., TUPIKOV Y. — 2015 г.
We report first thermodynamic measurements of the temperature derivative of chemical potential (∂μ/∂T ) in two-dimensional (2D) electron systems. In order to test the technique we have chosen Schottky gated GaAs/AlGaAs heterojunctions and detected experimentally in this 2D system quantum magnetooscillations of ∂μ/∂T. We also present a Lifshits-Kosevitch type theory for the ∂μ/∂T magnetooscillations in 2D systems and compare the theory with experimental data. The magnetic field dependence of the ∂μ/∂T value appears to be sensitive to the density of states shape of Landau levels. The data in low magnetic field domain demonstrate brilliant agreement with theory for non-interacting Fermi gas with Lorentzian Landau level shape.
THE COMMENSURABILITY CONDITION AND FRACTIONAL QUANTUM HALL EFFECT HIERARCHY IN HIGHER LANDAU LEVELS
JACAK J., JACAK L. — 2015 г.
The odd structure of the fractional filling hierarchy, which is referred to as the fractional quantum Hall effect, is studied in higher Landau levels using the commensurability condition. The hierarchy of fillings that are derived in this manner is consistent with the experimental observations in the first three Landau levels. The relative poverty of the fractional structure in higher Landau levels compared with the lowest Landau level is explained using commensurability topological arguments. The commensurability criterion for correlated states specific for higher Landau levels (with n > 1), including also the paired states at half fillings of the spin-subbands of these levels, is formulated.
THE EFFECT OF THE Ф 4 KINK’S INTERNAL MODE DURING SCATTERING ON PT-SYMMETRIC DEFECT
BORISOV D.I., DMITRIEV S.V., FATYKHOV M.A., JAVIDAN K., KEVREKIDIS P.G., SAADATMAND D. — 2015 г.
The effect of the φ 4 kink’s internal mode (IM) during the scattering from a PT-symmetric defect is investigated. It is demonstrated that if а ф 4 kink hits the defect from the gain side, a noticeable IM is excited, while for the kink coming from the opposite direction the mode excitation is much weaker. In the case when the kink initially carries IM, the IM amplitude is affected by the defect if the kink moves from the gain side and it is not affected when the kink moves in the opposite direction. A two degree of freedom collective variable model is shown to be capable of reproducing principal findings of the present work.