A. A. Golubov

Publications (296) View all

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  Available from: A. A. Golubov

  Article: Meissner effect in diffusive normal metal / d-wave superconductor junctions

  T Yokoyama, Y Tanaka, A. Golubov, J Inoue, Y Asano
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  ABSTRACT: The Meissner effect in diffusive normal metal / insulator / d-wave superconductor junctions is studied theoretically in the framework of the Usadel equation under the generalized boundary condition. The effect of midgap Andreev resonant states (MARS) formed at the interface of d-wave superconductor is taken into account. It is shown that the formation of MARS suppresses the susceptibility of the diffusive normal metal. Comment: 5 pages, 4 figures, Proceedings of the ISSP International Symposium (ISSP-9) on Quantum Condensed System
  10/2005;
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  Available from: A. A. Golubov

  Article: Comparative Description of the Microwave Surface Impedance of Nb, BaKBiO, and YBaCuO

  A. A. Golubov, M. R. Trunin, A. A. Zhukov, O. V. Dolgov, S. V. Shulga
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  ABSTRACT: Measurements of microwave impedance versus temperature, $Z_{\rm s}(T)$, in Nb, Ba$_{0.6}$K$_{0.4}$BiO$_3$, and YBa$_2$Cu$_3$O$_{7-\delta}$ are given. The measurements were made by the “hot finger” cavity perturbation technique. The electromagnetic properties of Nb are in a good quantitative agreement with the isotropic s-wave BCS theory. This model can also describe the experimental $Z_{\rm s}(T)$ curves in Ba$_{0.6}$K$_{0.4}$BiO$_3$ crystals if the nonhomogeneous broadening of the superconducting transition is properly taken into account. The behavior of the microwave impedance of YBa$_2$Cu$_3$O$_{7-\delta}$ disagrees with the isotropic BCS theory. This suggests a strong anisotropy of the order parameter in this compound. Since the controversy between s- and d-wave descriptions of YBa$_2$Cu$_3$O$_{7-\delta}$ properties has not been resolved yet, we have checked a simpler strongly anisotropic s-wave model. Calculations by this model have been compared to measurements on YBa$_2$Cu$_3$O$_{7-\delta}$. With due account of the strong-coupling effects, two-band anisotropy, and impurity scattering in YBa$_2$Cu$_3$O$_{7-\delta}$, the agreement between the generalized BCS model and experimental data is surprisingly good.
  Journal de Physique, I, 6, 2275 (1996). 12/2012;
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  Article: Stimulation of the Fluctuation Superconductivity by PT Symmetry.

  N M Chtchelkatchev, A A Golubov, T I Baturina, V M Vinokur
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  ABSTRACT: We discuss fluctuations near the second-order phase transition where the free energy has an additional non-Hermitian term. The spectrum of the fluctuations changes when the odd-parity potential amplitude exceeds the critical value corresponding to the PT-symmetry breakdown in the topological structure of the Hilbert space of the effective non-Hermitian Hamiltonian. We calculate the fluctuation contribution to the differential resistance of a superconducting weak link and find the manifestation of the PT-symmetry breaking in its temperature evolution. We successfully validate our theory by carrying out measurements of far from equilibrium transport in mesoscale-patterned superconducting wires.
  Physical Review Letters 10/2012; 109(15):150405. · 7.37 Impact Factor
• Article: Designing phase-sensitive tests for Fe-based superconductors

  A. A. Golubov, I. I. Mazin
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  ABSTRACT: We suggest new experimental designs suitable to test pairing symmetry in multiband Fe-based superconductors. These designs are based on combinations of tunnel junctions and point contacts and should be accessible by existing sample fabrication techniques.
  09/2012;
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  Available from: M. Yu. Kupriyanov

  Article: Double proximity effect in hybrid planar superconductor-(normal metal/ferromagnet)-superconductor structures

  T. E. Golikova, F. Hübler, D. Beckmann, I. E. Batov, T. Yu. Karminskaya, M. Yu. Kupriyanov, A. A. Golubov, V. V. Ryazanov
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  ABSTRACT: We have investigated the differential resistance of hybrid planar Al-(Cu/Fe)-Al submicron bridges at low temperatures and in weak magnetic fields. The structure consists of a Cu/Fe bilayer forming a bridge between two superconducting Al electrodes. In the superconducting state of Al electrodes, we have observed a double-peak peculiarity in differential resistance of the S-(N/F)-S structures at a bias voltage corresponding to the minigap. We claim that this effect (the splitting of the minigap) is due to an electron spin polarization in the normal metal which is induced by the ferromagnet. We have demonstrated that the double-peak peculiarity is converted to a single peak at a coercive applied field corresponding to zero magnetization of the Fe layer.
  Phys. Rev. B. 08/2012; 86(6).