The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform

R G Mints - One of the best experts on this subject based on the ideXlab platform.

  • Flux Creep in type ii superconductors the self organized criticality approach
    Physical Review B, 2005
    Co-Authors: R G Mints, Ilya Papiashvili
    Abstract:

    We consider the current density distribution function of a Flux Creep regime in type-II superconductors by mapping the Flux Creep process to the dynamics of a model with a self-organized criticality. We use an extremal Robin Hood type model which evolves to Been's type critical state to treat magnetic Flux penetration into a superconductor and derive an analog of the current-voltage characteristics in the Flux Creep region.

  • Flux Creep and Flux jumping
    Physical Review B, 1996
    Co-Authors: R G Mints
    Abstract:

    The Flux jump instability of Bean's critical state in the Flux-Creep regime of type-II superconductors is considered. We find the Flux-jump field ${\mathit{B}}_{\mathit{j}}$ which determines stability criterion of the superconducting state. The dependence of ${\mathit{B}}_{\mathit{j}}$ on the external magnetic-field ramp rate B${\mathrm{\ifmmode \dot{}\else \.{}\fi{}}}_{\mathit{e}}$ is calculated. We demonstrate that under the conditions typical for most of the magnetization experiments the slope of the current-voltage curve in the Flux-Creep regime determines the stability of the Bean's critical state, i.e., the value of ${\mathit{B}}_{\mathit{j}}$. We show that a Flux jump can be preceded by magnetothermal oscillations and find the frequency of these oscillations as a function of B${\mathrm{\ifmmode \dot{}\else \.{}\fi{}}}_{\mathit{e}}$. \textcopyright{} 1996 The American Physical Society.

I. L. Landau - One of the best experts on this subject based on the ideXlab platform.

  • Critical currents, Flux-Creep activation energy, and potential barriers for the vortex motion from Flux-Creep experiments
    Physical Review B, 2001
    Co-Authors: I. L. Landau
    Abstract:

    We present an experimental study of thermally activated Flux Creep in a superconducting ring-shaped epitaxial YBCO film as well as a new way of analyzing the experimental data. The measurements were made in a wide range of temperatures between 10 and 83 K. The upper temperature limit was dictated by our experimental technique and at low temperatures we were limited by a crossover to quantum tunneling of vortices. It is shown that the experimental data can very well be described by assuming a simple thermally activated hopping of vortices or vortex bundles over potential barriers, whereby the hopping Flux objects remain the same for all currents and temperatures. The new procedure of data analysis also allows to establish the current and temperature dependencies of the Flux-Creep activation energy U, as well as the temperature dependence of the critical current Ic, from the Flux-Creep rates measured at different temperatures. The variation of the activation energy with current, U(I/Ic), is then used to reconstruct the profile of the potential barriers in real space.

  • Thermally activated Flux Creep in YBa2Cu3O7−x film
    Physica C-superconductivity and Its Applications, 2000
    Co-Authors: I. L. Landau
    Abstract:

    Abstract We report on a study of thermally activated Flux Creep in a ring-shaped epitaxial YBa 2 Cu 3 O 7− x film over a wide range of temperatures, using an experimental technique that allows us to obtain voltage–current ( V – I ) characteristics of the sample at low voltages without electric contacts to the film. It is shown that in the temperature range between 10 and 60 K, the Flux Creep can be described in terms of a thermally activated hopping of vortices over potential barriers. Taking into account the temperature dependence of the critical current, all V – I characteristics in the above temperature range may be merged onto a single continuous curve, from which the current dependence of the activation energy for 0.4 I / I c

  • Influence of weak visible light on Flux Creep in HTSC at low temperatures
    Superlattices and Microstructures, 1997
    Co-Authors: I. L. Landau, Leo Rinderer
    Abstract:

    Abstract We present an experimental study of Flux Creep in YBCO film at low temperatures (1.3 K

  • Influence of weak visible light on Flux Creep in YBCO film at low temperatures
    Physica C-superconductivity and Its Applications, 1995
    Co-Authors: I. L. Landau, Leo Rinderer
    Abstract:

    Abstract We present an experimental study of Flux Creep in YBCO film. A ring-shaped film was used to directly obtain voltage-current characteristics of the film in a Flux Creep regime. It is shown that the Flux Creep can be described in terms of quantum tunneling of vortices up to temperatures of 10–15 K. We have also investigated the influence of weak illumination on Flux Creep rate. It is shown that visible light with intensity less than 1 mW/cm 2 drastically accelerates the Flux Creep at liquid helium temperatures. The influence of light is completely different to that caused by the temperature rise. We propose a simple qualitative model to explain the high sensitivity of the Flux Creep to weak illumination.

Richard S Thompson - One of the best experts on this subject based on the ideXlab platform.

  • quantum Flux Creep in layered high tc superconductors
    Physical Review B, 1991
    Co-Authors: Boris I. Ivlev, Yu N Ovchinnikov, Richard S Thompson
    Abstract:

    Quantum Flux Creep in sufficiently perfect layered high-{ital T}{sub {ital c}} superconductors is shown to be possible when the magnetic field is parallel to the layers. The crossover temperature between activated and quantum Creep is found as a function of the transport current, normal resistivity, and upper critical field. Quantum Creep can be observable if the transport current is high enough.

Ilya Papiashvili - One of the best experts on this subject based on the ideXlab platform.

Boris I. Ivlev - One of the best experts on this subject based on the ideXlab platform.

  • quantum Flux Creep in layered high tc superconductors
    Physical Review B, 1991
    Co-Authors: Boris I. Ivlev, Yu N Ovchinnikov, Richard S Thompson
    Abstract:

    Quantum Flux Creep in sufficiently perfect layered high-{ital T}{sub {ital c}} superconductors is shown to be possible when the magnetic field is parallel to the layers. The crossover temperature between activated and quantum Creep is found as a function of the transport current, normal resistivity, and upper critical field. Quantum Creep can be observable if the transport current is high enough.

  • Flux Creep in layered high-Tc superconductors
    Physica B-condensed Matter, 1990
    Co-Authors: Boris I. Ivlev, N. B. Kopnin
    Abstract:

    We study a Flux Creep when the magnetic field is parallel to the layers (the Cu-0 planes) and vortices move across them. The pinning of vortices results from their interaction with the layered structure of the superconductor.

  • Flux Creep and Flux pinning in layered high temperature superconductors
    Physical Review Letters, 1990
    Co-Authors: Boris I. Ivlev, N. B. Kopnin
    Abstract:

    For a high-${\mathit{T}}_{\mathit{c}}$ layered superconductor, we study a Flux Creep when the magnetic field is parallel to the layers (the CU-O planes) and vortices move across them. In a homogeneous material, the pinning of vortices results from their interaction with the layered structure of the superconductor provided the vortex-lattice period is commensurate with the interlayer spacing. The Flux-Creep activation energy is proportional to ${\mathit{j}}^{\mathrm{\ensuremath{-}}1}$ at small currents due to a large size of the activated vortex bundle.