M. V. Simkin

Publications (3)0 Total impact

• Source

  Available from: arxiv.org

  Article: Edge effects in a frustrated Josephson junction array with modulated couplings

  E. Granato, J. M. Kosterlitz, M. V. Simkin
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  ABSTRACT: A square array of Josephson junctions with modulated strength in a magnetic field with half a flux quantum per plaquette is studied by analytic arguments and dynamical simulations. The modulation is such that alternate columns of junctions are of different strength to the rest. Previous work has shown that this system undergoes an XY followed by an Ising-like vortex lattice disordering transition at a lower temperature. We argue that resistance measurements are a possible probe of the vortex lattice disordering transition as the linear resistance $R_{L}(T)\sim A(T)/L$ with $ A(T) \propto (T-T_{cI})$ at intermediate temperatures $T_{cXY}>T>T_{cI}$ due to dissipation at the array edges for a particular geometry and vanishes for other geometries. Extensive dynamical simulations are performed which support the qualitative physical arguments. Comment: 8 pages with figs, RevTeX, to appear in Phys. Rev. B
  10/1997;
• Source

  Available from: arxiv.org

  Article: Numerical Study of a Superconducting Glass Model

  J. M. Kosterlitz, M. V. Simkin
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  ABSTRACT: An XY model with random phase shifts as a model for a superconducting glass is studied in two and three dimensions by a zero temperature domain wall renormalization group which allows one to follow the flows of both the coupling constant and the disorder strength with increasing length scale. Weak disorder is found to be marginal in two and probably irrelevant in three dimensions. For strong disorder the flow is towards a non-superconducting gauge glass fixed point in 2d and a superconducting glass in 3d. Our results are in agreement with recent analytic theory and are inconsistent with earlier predictions of a re-entrant transition to a disordered phase at very low temperature and with the loss of superconductivity for any finite amount of disorder.
  02/1997;
• Source

  Available from: arxiv.org

  Article: Finite Size and Current Effects on IV Characteristics of Josephson Junction Arrays

  M. V. Simkin, J. M. Kosterlitz
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  ABSTRACT: The effects of finite size and of finite current on the current-voltage characteristics of Josephson junction arrays is studied both theoretically and by numerical simulations. The cross-over from non-linear to linear behavior at low temperature is shown to be a finite size effect and the non-linear behavior at higher temperature, $T>T_{KT}$, is shown to be a finite current effect. These are argued to result from competition between the three length scales characterizing the system. The importance of boundary effects is discussed and it is shown that these may dominate the behavior in small arrays. Comment: 5 pages, figures included, to appear in PRB
  10/1996;