Архив научных статейиз журнала «Письма в "Журнал экспериментальной и теоретической физики"»

EVIDENCE ON THE MACROSCOPIC LENGTH SCALE SPIN COHERENCE FOR THE EDGE CURRENTS IN A NARROW HGTE QUANTUM WELL. IN MEMORY OF V.F.GANTMAKHER
DEVIATOV E.V., DVORETSKY S.A., EGOROV S.V., KONONOV A., KVON Z.D., MIKHAILOV N.N. — 2015 г.
We experimentally investigate spinpolarized electron transport between two ferromagnetic contacts, placed at the edge of a twodimensional electron system with band inversion. The system is realized in a narrow (8 nm) HgTe quantum well, the ferromagnetic side contacts are formed from a premagnetized permalloy film. In zero magnetic field, we find a significant edge current contribution to the transport between two ferromagnetic contacts. We experimentally demonstrate that this transport is sensitive to the mutual orientation of the magnetization directions of two 200 /xmspaced ferromagnetic leads. This is a direct experimental evidence on the spincoherent edge transport over the macroscopic distances. Thus, the spin is extremely robust at the edge of a twodimensional electron system with band inversion, confirming the helical spinresolved nature of edge currents.

EXCITATION WAVE PROPAGATION IN A PATTERNED MULTIDOMAIN CARDIAC TISSUE
AGLADZE K.I., KUDRYASHOVA N.N., ORLOVA Y.V., TEPLENIN A.S. — 2015 г.
Electrospun fibrous mats are widely used in the contemporary cardiac tissue engineering as the substrates for growing cardiac cells. The substrate with chaotically oriented nanofibers leads to the growth of cardiac tissue with randomly oriented, but internally morphologically anisotropic clusters or domains. The domain structure affects the stability of the excitation propagation and we studied the stability of the propagating excitation waves versus the average size of the domains and the externally applied excitation rate. In an experimental model based on neonatal rat cardiac tissue monolayers, as well as in the computer simulations we found that increase of domain sizes leads to the decrease of the critical stimulation frequencies, thus evidencing that larger domains are having a higher arrhythmogenic effect.

FAST RADIO BURSTS AND AXION MINICLUSTERS
TKACHEV I.I. — 2015 г.
Nonlinear effects in the evolution of the axion field in the early Universe may lead to the formation of gravitationally bound clumps of axions, known as “miniclusters.” Minicluster masses should be in the range M rnc ~ 1O 12M ⊙, and in plausible earlyUniverse scenarios a significant fraction of the mass density of the Universe may be in the form of axion miniclusters. Here I argue that observed properties (total energy release, duration, high brightness temperature, event rate) of recently discovered Fast Radio Bursts can be matched in a model which assumes explosive decay of axion miniclusters.

FEMTOSECOND PULSE SHAPING WITH PLASMONIC CRYSTALS
BESSONOV V.O., DOLGOVA T.V., FEDYANIN A.A., SHCHERBAKOV M.R., VABISHCHEVICH P.P. — 2015 г.
The temporal shaping of femtosecond laser pulses reflected from a onedimensional plasmonic crystal using a commercially available polymer grating coated with a silver film is experimentally demonstrated by timeresolved measurements of the intensity correlation function. Shaping is achieved by the excitation of surface plasmonpolaritons with a lifetime comparable to the 130 fs laser pulse duration. The variety of data obtained demonstrate the flexible shaping of fspulses by delaying, advancing, splitting, broadening, compressing, and changing the topological properties of the pulse with the plasmonic crystals under study.

FERROMAGNETISM MEDIATED BY THE UPPER HUBBARD BAND IN SELECTIVELY DOPED GAAS/ALGAAS STRUCTURES 250
AGRINSKAYAL N.V., KOZUB V.I. — 2015 г.
We consider in detail the indirect exchange between Mn ions imbedded to GaAs/AlGaAs quantum wells where the barriers are doped by acceptor impurity supported by the carriers of the upper Hubbard band supplied by barriers acceptors. A special attention is paid to an interplay between strong delocalization of the carriers within the upper Hubbard band (allowing exchange between well separated ions) and relatively weak coupling of these carriers with Mn ions. It is shown, that, despite of the latter factor, the values of Curie temperatures can for such structures be as high as room temperatures.

IN SITU ИССЛЕДОВАНИЕ АТОМНОВАКАНСИОННОГО УПОРЯДОЧЕНИЯ В МОНООКСИДЕ ТИТАНА СТЕХИОМЕТРИЧЕСКОГО СОСТАВА МЕТОДОМ МАГНИТНОЙ ВОСПРИИМЧИВОСТИ
ВАЛЕЕВА А.А., НАЗАРОВА С.З., РЕМПЕЛЬ А.А. — 2015 г.
С помощью метода магнитной восприимчивости проведено in situ температурное исследование изменения степени дальнего порядка в монооксиде титана стехиометрического состава. Измерения проведены на отожженном и закаленном монооксидах титана в интервале температур от 300 до 1200 К. Обнаружено, что величина степени дальнего порядка зависит от режима и температуры отжига исходных образцов. Степень дальнего порядка в процессе измерения магнитной восприимчивости от 0.21 до 1.00, причем чем больше величина степени дальнего порядка, тем меньше величина магнитной восприимчивости. Кроме того, параметр дальнего порядка понижается при увеличении температуры выше 1200 К. При достижении температуры перехода порядокбеспорядок он резко уменьшается до нуля. Согласно результатам данной работы критический параметр дальнего порядка равен 0.21, а температура неравновесного перехода беспорядокпорядок составляет около 1073 К.

INTERACTIONINDUCED MERGING OF LANDAU LEVELS IN AN ELECTRON SYSTEM OF DOUBLE QUANTUM WELLS IN MEMORY OF V.F.GANTMAKHER
CLARK J.W., DOLGOPOLOV V.T., KHODEL V.A., SBASBKIN A.A., SHAGINYAN V.R., ZVEREV M.V. — 2015 г.
We show that the disappearance of the chemical potential jumps over the range of perpendicular magnetic fields at fixed integer filling factor in a double quantum well with a tunnel barrier is caused by the interaction induced level merging. The distribution function in the merging regime is special in that the probability to find an electron with energy equal to the chemical potential is different for the two merged levels.

INTERVALLEY SCATTERING BY CHARGED IMPURITIES IN GRAPHENE
BRAGINSKY L.S., ENTIN M.V. — 2015 г.
Intervalley chargedimpurity scattering processes are examined. It is found that the scattering probability is enhanced due to the Coulomb interaction with the impurity by the Sommerfield factor Fz ∞ ε 2√14g 22, where ε is the electron energy and g is the dimensionless constant of the Coulomb interaction.

JOSEPHSON EFFECT IN SIFS TUNNEL JUNCTIONS WITH DOMAIN WALLS IN WEAK
BAKURSKIY S.V., GOLUBOVX A.A., KLENOV N.V., KUPRIYANOVOV M. YU., SOLOVIE I.I. — 2015 г.
We study theoretically the properties of SIFS type Josephson junctions composed of two superconducting (S) electrodes separated by an insulating layer (I) and a ferromagnetic (F) film consisting of periodic magnetic domains structure with antiparallel magnetization directions in neighboring domains. The twodimensional problem in the weak link area is solved analytically in the framework of the linearized quasiclassieal Usadel equations. Based on this solution, the spatial distributions of the critical current density, Jc, in the domains and critical current, Ic, of SIFS structures are calculated as a function of domain wall parameters, as well as the thickness, d_p, and the width, W, of the domains. We demonstrate that IcidF,W) dependencies exhibit damped oscillations with the ratio of the decay length, £i, and oscillation period, £2, being a function of the parameters of the domains, and this ratio may take any value from zero to unity. Thus, we propose a new physical mechanism that may explain the essential difference between £1 and £2 observed experimentally in various types of SFS Josephson junctions.

LONGRANGE SPIN IMBALANCE IN MESOSCOPIC SUPERCONDUCTORS UNDER A ZEEMAN SPLITTING
BOBKOV A.M., BOBKOVA I.V. — 2015 г.

MAGNETIC SUSCEPTIBILITY OF THE QUARK MATTER IN QCD
ORLOVSKY V.D., SIMONOV YU.A. — 2015 г.
Magnetic susceptibility in the deconfined phase of QCD is calculated in a closed form using a recent general expression for the quark gas pressure in magnetic field. Quark selfenergies are entering the result via Polyakov line factors and ensure the total paramagnetic effect, increasing with temperature. A generalized form of magnetic susceptibility in nonzero magnetic field suitable for experimental and lattice measurements is derived, showing a good agreement with available lattice data.

MATRIX INTEGRAL EXPANSION OF COLOURED JONES POLYNOMIALS FOR FIGUREEIGHT KNOT
ALEXANDROV A., MELNIKOV D. — 2015 г.
In this note we examine a possible extension of the matrix integral representation of knot invariants beyond the class of torus knots. In particular, we study a representation of the SU{2) quantum Racah coefficients by double matrix integrals. We find that the Racah coefficients are mapped to expansion coefficients in some basis of double integrals. The transformed coefficients have a number of interesting algebraic properties.

MEASUREMENTS OF ANISOTROPIC MASS OF MAGNONS CONFINED IN A HARMONIC TRAP IN SUPERFLUID 3HEВ
AUTTI S., ELTSOV Y.B., HEIKKINEN P.J., ZAVJALOV V.V. — 2015 г.
We can pump magnons to a nearly harmonic magnetotextural trap in superfluid 3HeB. Using the NMR spectroscopy of levels in the trap we have measured the anisotropic magnon mass and related values of the spinwave velocities. Based on our measurements we provide values of the Fermiliquid parameter F a 1

OBSERVATION OF A POLARIZATION STRUCTURE IN INELASTIC 40CA(P,P'')~K. REACTION AT 1 GEV
AMALSKY G.M., ANDREEV V.A., GAVRILOV G.E., IZOTOV A.A., KISSELEV A. YU., KOZLENKO N.G., KRAVCHENKO P.V., LEVCHENKO M.P., MIKLUKHO O.V., NOVINSKIY D.V., PROKOFIEV A.N., SBVEDCBIKOV A.V., TTUSB S.I., ZHDANOV A.A. — 2015 г.
The polarization ol the secondary protons in the inelastic (p,p'') reaction on the 40Ca nucleus at the initial proton energy 1 GeV was measured in a wide range ol the scattered proton momenta at a laboratory angle 0 = 21°. The final protons from the reaction were detected using the magnetic spectrometer equipped with multiwireproportional chambers polarimeter. A structure ol the polarization data, related probably to scattering off the nucleon correlations in the nucleus, was observed.

OCCURRENCE OF FLAT BANDS IN STRONGLY CORRELATED FERMI SYSTEMS AND HIGHT C SUPERCONDUCTIVITY OF ELECTRONDOPED COMPOUNDS
CLARK J.W., KHODEL Y.A., POPOV K.G., SHAGINYAN Y.R. — 2015 г.
We consider a class of strongly correlated Fermi systems that exhibit an interactioninduced flat band pinned to the Fermi surface, and generalize the Landau strategy to accommodate a flat band and apply the more comprehensive theory to electron systems of solids. The nonFermiliquid behavior that emerges is compared with relevant experimental data on heavyfermion metals and electrondoped highT c compounds. We elucidate how heavyfermion metals have extremely low superconducting transition temperature T c, its maximum reached in the heavyfermion metal CeCoIng does not exceed 2.3 K, and explain the enhancement of T c observed in highT c superconductors. We show that the coefficient Ai of the Tlinear resistivity scales with T c, in agreement with the experimental behavior uncovered in the electrondoped materials. We have also constructed schematic temperaturedoping phase diagram of the copper oxide superconductor La 2xCe xCuO 4 and explained the doping dependence of its resistivity.

ODMR EVIDENCE OF ELECTRONIC CASCADE IN MULTIPLE ASYMMETRICAL (CDMN)TE QUANTUM WELLS
BARANOV P.G., GURIN A.S., KARCZEWSKI G., KUSTAYEV YU.G., NAMOZOV B.R., ROMANOV N.G., TOLMACHEV D.O. — 2015 г.
Exchangecoupled complexes consisting of Mn ions and holes were revealed by optically detected magnetic resonance in the narrowest quantum wells of asymmetrical multiplequantumwell structures (CdMn)Te/(CdMg)Te. Calculations were performed to estimate the parameters of the complexes (exchange interactions and hole (gfactors) and simulate the spectra. The formation of such complexes implies the directional electron tunneling from narrow to larger wells, i.e. an electronic cascade, which results in the creation of the excess hole concentration in the narrowest and intermediatewidth quantum wells.

ON FORMATION OF EQUATION OF STATE OF EVOLVING QUANTUM FIELD
LEONIDOV A.V., RADOVSKAYA A.A. — 2015 г.
Stylized model of evolution of matter created in ultrarelativistic heavy ion collisions is considered. Systematic procedure of computing quantum corrections in the framework of Keldysh formalism is formulated. Analytical expressions for formation of equations of state taking into account leading quantum corrections are worked out, complete description of sub leading corrections and analytical expressions for some of them are presented.

ON THE BEHAVIOR OF SCATTERING PHASES IN COLLISIONS OF ELECTRONS WITH MULTIATOMIC OBJECTS
AMUSIA M.YA., CHERNYSHEVA L.V. — 2015 г.
We have studied the energy dependence of several first scattering phases with multiatomic object. As concrete examples representing the general trends endohedrals Ne@C6o and Аг@С 60 are considered. It appeared that the presence of an inner atom, either Ne or Ar, qualitatively affects the scattering phases, in spite of the fact that the fullerene consists of 60 carbon atoms, while the atom staffed inside is only one. Calculations are performed in the oneelectron HartreeFock (HF) and random phase approximation with exchange (RPAE) for the inner atom while the fullerenes shell is substituted by static potential without and with the polarization potential. It appeared that the total endohedral scattering phase is simply a sum of atomic, Ne or Ar, and fullerenes С 60 phases, contrary to the intuitive assumption that the total phases on С 60 and Ne@C6o or Аг@С 60 has to be the same.

ON THE DEFECT AND STABILITY OF DIFFERENTIAL EXPANSION
KONONOV YA., MOROZOV A. — 2015 г.
Empirical analysis of many colored knot polynomials, made possible by recent computational advances in ChernSimons theory, reveals their stability: for any given negative N and any given knot the set of coefficients of the polynomial in rth symmetric representation does not change with r, if it is large enough. This fact reflects the nontrivial and previously unknown properties of the differential expansion, and it turns out that from this point of view there are universality classes of knots, characterized by a single integer, which we call defect, and which is in fact related to the power of Alexander polynomial.

ON THE SCATTERING OF DNA REPLICATION COMPLETION TIMES
FARZETDINOVA R.M., MEILIKHOV E.Z. — 2015 г.
Stochasticity of Eukaryotes’ DNA replication should not lead to large fluctuations of replication times which could result in mitotic catastrophes. Fundamental problem that cells face is how to be ensured that entire genome is replicated on time. We develop analytic approach of calculating DNA replication times, that being simplified and approximate, leads, nevertheless, to results practically coincident with those which have been obtained by some sophisticated methods. In the framework of that model we consider replication times’ scattering and discuss the influence of repair stopping on kinetics of DNA replication. Our main explicit formulae for DNA replication time t r ∝√lnN (N is the total number of DNA base pairs) is of general character and explains basic features of DNA replication kinetics.