Publications (81)51.05 Total impact

Article: Upper critical field in electrondoped cuprate superconductor Nd2−xCexCuO4+δ: Twogap model
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ABSTRACT: We present resistivity measurements of the upper critical field (Hc2) phase diagram as a function of temperature (T) for Nd1.85Ce0.15CuO4+δ/SrTiO3 single crystal films with different degree of disorder (δ) in magnetic fields up to 90 kOe at temperatures down to 0.4 K. The data are well described by a twoband/twogap model for a superconductor in the dirty limit.Physica C Superconductivity 05/2013; 488:25–29. · 0.72 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Temperature and magneticfield dependences of longitudinal ρxx(B,T) and Hall ρxy(B,T) resistivities of nInxGa1−xAs/GaAs nanostructures with single and double quantum wells are investigated in the quantum Hall regime at B = 0–16 Т and T = 0.05–70 K, before and after IR illumination. The temperature dependence of the QHE plateauplateau transition width is analyzed and information about temperature dependences of the bandwidth of delocalized states in the center of Landau subbands is obtained.Low Temperature Physics 01/2013; 39(1). · 0.82 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The longitudinal ρxx (B) and Hall ρxy (B) magnetoresistances are investigated experimentally in the integer quantum Hall effect (QHE) regime in nInGaAs/GaAs double quantum well nanostructures in the range of magnetic fields B = (0–16) T and temperatures T = (0.05–70) K before and after IR illumination. The results are evaluated within the scaling hypothesis with regard to electronelectron interaction.Journal of Experimental and Theoretical Physics 01/2013; 117(1). · 0.92 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present resistivity measurements of the upper critical field (H$_{c2}$) phase diagram as a function of temperature (T) for Nd$_{1.85}$Ce$_{0.15}$CuO$_{4+\delta}$/SrTiO$_3$ single crystal films with different degree of disorder ($\delta$) in magnetic fields up to 90 kOe at temperatures down to 0.4 K. The data are well described by a twoband/twogap model for a superconductor in the dirty limit.12/2012;  [Show abstract] [Hide abstract]
ABSTRACT: Transport properties of Nd2−xCexCuO4+δ/SrTiO3 single crystal films (B‖c,J‖abB‖c,J‖ab) are investigated in magnetic fields B up to 9T at T = (0.4–4.2) K. An analysis of normal state (at B>Bc2B>Bc2) Hall coefficient RHn dependence on Ce doping takes us to a conclusion about the existence both of electronlike and holelike contributions to transport in nominally electrondoped system. In accordance with RHn(x) analysis an anomalous sign reversal of Hall effect in mixed state at B<Bc2B<Bc2 may be ascribed to a fluxflow regime for two types of carriers with opposite charges.Physica C Superconductivity 12/2012; 483:113–118. · 0.72 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The resistivity (ρ) of low mobility dilute 2D electron gas in an nInGaAs/GaAs double quantum well (DQW) exhibits the monotonic "insulatinglike" temperature dependence (dρ/dT < 0) at T = 1.8–70 K in zero magnetic field. This temperature interval corresponds to a ballistic regime (kBTτ/ħ > 0.1–3.5) for our samples, and the electron density is on an "insulating" side of the socalled B = 0 2D metal–insulator transition. We show that the observed features of localization and Landau quantization in a vicinity of the low magneticfieldinduced insulator–quantum Hall liquid transition is due to the σxy(T) anomalous Tdependence.International Journal of Nanoscience 11/2011; 06(03n04).  [Show abstract] [Hide abstract]
ABSTRACT: The inplane resistivity, Hall effect (T = 77 K) and SCtransition for some Nd1.85Ce0.15CuO4+δ single crystal films are investigated at different nonstoichiometric disorder (δ). It is shown that with increasing of δ the Hallcoefficient for the most of the samples differs no more than twice but the normal state resistivity increases by a factor of five. SCtransition temperature decreases with essential broadening of the transition region. The observed evolution from homogeneous metallic (and superconducting) Nd1.85Ce0.15CuO4+δ system to inhomogeneous dielectric one is described as Andersontype disorderinduced transition in a twodimensional electron system.Modern Physics Letters B 11/2011; 17(10n12). · 0.48 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Transport properties of Nd$_{2x}$Ce$_x$CuO$_{4+\delta}$ single crystal films are investigated in magnetic fields $B$ up to 9T at $T$=(0.44.2)K. An analysis of normal state (at $B>B_{c2}$) Hall coefficient $R_H$$^n$ dependence on Ce doping takes us to a conclusion about the existence both of electronlike and holelike contributions to transport in nominally electrondoped system. In accordance with $R_H$$^n$(x) analysis an anomalous sign reversal of Hall effect in mixed state at $B<B_{c2}$ may be ascribed to a fluxflow regime for two types of carriers with opposite charges.09/2011;  [Show abstract] [Hide abstract]
ABSTRACT: The lowtemperature upper critical field is measured for single crystal Nd2xCexCuO4+delta with different values of x and nonstoichiometric disorder (delta). The coherence length for pair correlation xi and the product kFxi, where kF is the Fermi wave vector, are estimated. It is shown that the parameter kFxi≅100 for these single crystals, so that, phenomenologically, the NdCeCuOsystem is in the domain of Cooperpairbased (BCS) superconductivity.Low Temperature Physics 01/2011; 37:293295. · 0.82 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Magnetoresistivity and the Hall effect measured in magnetic fields up to B=9 T (Bc,Jab) in electrondoped Nd2xCexCuO4+delta single crystal films with x=0.14, 0.15, and 0.18 and different oxygen contents (delta) were studied for temperatures in the range 0.44.2 K. The behavior of the resistivity and Hall coefficient in the mixed state are discussed in terms of a fluxflow model including a vortex counterflow owing to pinning forces.Low Temperature Physics 01/2011; 37:268271. · 0.82 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Results of lowtemperature upper critical field measurements for Nd$_{2x}$Ce$_x$CuO$_{4+\delta}$ single crystals with various $x$ and nonstoichiometric disorder ($\delta$) are presented. The coherence length of pair correlation $\xi$ and the product $k_F$$\xi$, where $k_F$ is the Fermi wave vector, are estimated. It is shown that for investigated single crystals parameter $k_F$$\xi$ $\cong$ 100 and thus phenomenologically NdCeCuO  system is in a range of Cooperpairbased (BCS) superconductivity. Comment: 8 pages, 3 figures, 2 tables10/2010;  [Show abstract] [Hide abstract]
ABSTRACT: Magnetoresistivity and Hall effect measured in magnetic fields up to B=9T (Bc, Jab) in electrondoped $Nd_{2x}$Ce_{x}Cu$O_{4+{\delta}} single crystal films with x = 0.14; 0.15; 0.18 and different oxygen content ({\delta}) were studied in a temperature range of 0.44.2 K. The resistivity and Hall coefficient behaviors in the mixed state are discussed in the framework of fluxflow model with the inclusion of the backflow of vortices owing to the pinning forces. Comment: 8 pages, 4 figures, 2 tables10/2010;  [Show abstract] [Hide abstract]
ABSTRACT: Hall effect and magnetoresistivity measured in magnetic fields up to B=9T (B∥c,J∥ab) in electrondoped Nd2−xCexCuO4+δ single crystal films with x=0.14; 0.15 and different oxygen content (δ) were studied in a temperature range of 0.4–40K. It was found that for the optimally doped Nd2−xCexCuO4+δ (x=0.15) the heat treatment (annealing) under various conditions leads to the decrease of the disorder parameter, charge carriers delocalization and considerable increase of the mean free path. On the other hand, charge carriers concentration and mean free path were practically independent on the heat treatment conditions for underdoped compounds (x=0.14).Physica C Superconductivity 01/2010; 470. · 0.72 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A semiclassical calculation of the spectrum of Landau levels in an inclined magnetic field is performed for a double quantum well taking account of the energy dependences of the cyclotron effective masses. A comparison is made with a quantummechanical calculation in weak perpendicular magnetic fields (N. Kumada &etal;, Phys. Rev. B 77, 155324 (2008)). It is found that both computational methods are in good agreement with one another.Low Temperature Physics 02/2009; 35(2). · 0.82 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Qualitatively different temperature dependences of quantum Hall transition width are observed for heterostructures with shortrange (InGaAs/GaAs) or smooth (Ge/GeSi) impurity potentials. As the real scaling behavior, with critical exponent close to the theoretical value, has been observed at the former, the semiclassical in nature dependences takes place at the latter, in accordance with available theoretical considerations.Physica B Condensed Matter 01/2009; 404(23):51925195. · 1.33 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Temperature dependences of the electrical resistivity measured in different magnetic fields (B ∥ c, J ∥ ab) of electron doped Nd2−x Ce x CuO4+δ single crystals with different cerium concentration (x=0.15, 0.17, and 0.20) and oxygen content (δ) were studied in a temperature range of 1.8–40 K. It was found that the slope of the upper critical field decreases with the increase of the disorder in the system. So, we can distinguish experimentally dwave and anisotropic swave superconductors. Moreover, the slope of the upper critical field and critical temperature decrease with increase of the disorder parameter like in dwave superconductors with anisotropic scattering.Journal of Superconductivity and Novel Magnetism 01/2009; 22(1):2124. · 0.70 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The temperature dependences of the resistivity of singlecrystal films of the Nd2 − x Ce x CuO4 + δ ntype superconductors with x = 0.14 (underdoped region) and x = 0.15 (optimal doping region) and different degrees of disorder δ have been investigated in various magnetic fields (B ‖ c, J ‖ ab) in the temperature range 0.4–300 K. It has been demonstrated that there are differences in the behavior of the dependences of the slope of the upper critical field $ (dB_{c2} /dT)_{T \to T_c } $ (dB_{c2} /dT)_{T \to T_c } on the disorder parameter for the underdoped samples (x = 0.14) and the samples with the optimal doping (x = 0.15). The study of the dependence of the slope of the upper critical field on the degree of disorder has made it possible to discriminate experimentally between the superconductors with the d pairing and anisotropic s pairing. It has been revealed that the relative stability of the ntype superconductor with the optimal doping with respect to disordering is possibly due to the strong anisotropy of impurity scattering with symmetry of the d type.Physics of the Solid State 01/2009; 51(11):22292234. · 0.77 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The temperature and magneticfield dependence of the components of the conductivity and resistivity tensors are calculated with the quantum corrections due to the weak localization effect and electronelectron interaction taken into account in the diffusion and ballistic regimes. The corrections to the conductivity from the weak localization and electronelectron interaction and also the influence of spin and oscillation effects are taken into account by a renormalization of the transport relaxation time of the electron momentum, with the result that the Drude conductivity becomes temperature dependent. A calculation of the components of the conductivity and resistivity tensors is carried out with the use of the theoretical values of the parameters of the theory of quantum corrections, which are determined solely by the values of the carrier density and mobility of a particular sample. The results of the calculation are compared with experimental results for twodimensional nInGaAs/GaAs structures with double quantum wells. It is shown that taking only the quantum corrections into account with the theoretical values of the parameters does not permit even a qualitative description of experiment, and it is therefore necessary to take additional temperaturedependent contributions to the Drude conductivity into account.Low Temperature Physics 01/2009; 35:3243. · 0.82 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Development of quantum Hall peculiarities due to mobility gap between spinsplit magnetic levels with addition of the parallel magnetic field component B  is analyzed in double quantum wells (DQW) created in InGaAs/GaAs and InAs/AlSb heterosystems chosen due to their relatively large bulk gfactors. In InGaAs/GaAs DQWs, the nonmonotonous behavior of these peculiarities is observed and explained within singleelectron approach in terms of competition between enhanced spin splitting and localization of electrons in the layers of DQW with increased B  . In InAs/AlSb DQW, the tunneling connection between the layers is very weak due to high barrier, nevertheless the collective oddnumbered peculiarities are revealed that exist due to spontaneous interlayer phase coherence. B  destroys these states that is manifested, in particular, in the suppression of the peculiarity for filling factor ν = 3.Journal of Physics Conference Series 01/2009; 150(2).  [Show abstract] [Hide abstract]
ABSTRACT: The temperature dependences of the resistance of the Nd2−x Ce x CuO4+δ single crystal with x = 0.15 and various disorder parameters δ have been investigated in various magnetic fields (B ‖ c, J ‖ ab) in the temperature range T = 1.8–40 K. It has been shown that the slope of the upper critical field, (dB c2/dT)T c, in the electron superconductor decreases with an increase in the disorder parameter. This dependence makes it possible to experimentally distinguish between dpairing superconductors and spairing superconductors. The dependence of the superconducting transition temperature on the disorder parameter in the system is investigated in the model of the superconductors with anisotropic impurity scattering.JETP Letters 01/2008; 88(2):123126. · 1.52 Impact Factor
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86  Citations  
51.05  Total Impact Points  
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Institutions

1996–2013

Institute of Metal Physics
Sverolovsk, Sverdlovsk, Russia 
Kurchatov Institute
Moskva, Moscow, Russia


1997–2011

Russian Academy of Sciences
 Institute of Metal Physics
Moskva, Moscow, Russia
