Sökning: "Kosterlitz-Thouless transition"

Visar resultat 1 - 5 av 9 avhandlingar innehållade orden Kosterlitz-Thouless transition.

  1. 1. Vortex fluctuations in superconductors

    Författare :Peter Olsson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Superconductor; Two dimensions; vortex; coulomb gas; XY model; Kosterlitz-Thouless transition; high-Tc.;

    Sammanfattning : The vortex fluctuations have proved to be responsible for the onset of dissipation in thin type-II superconducting Aims. There is also growing evidence that dissipation in high- temperature superconductors exhibits the same kind of two-dimensional (2D) behavior. LÄS MER

  3. 2. On the Zero and Low Field Vortex Dynamics : An Experimental Study of Type-II Superconductors

    Författare :Örjan Festin; Peter Svedlindh; Piero Martinoli; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; high temperature superconductors; thermal fluctuations; YBCO; MgB2; anisotropic superconductors; vortex dynamics; Kosterlitz-Thouless transition; current voltage characteristics; complex conductivity; Flux noise; Teknisk fysik; Engineering physics; Teknisk fysik;

    Sammanfattning : Dynamic properties of type-II superconductors have been experimentally studied in zero and low magnetic fields using SQUID magnetometry and I–V measurements.In zero magnetic field close to the critical temperature, the physical properties of type-II superconductors are dominated by spontaneously created vortices. LÄS MER

  4. 3. Characteristic properties of two-dimensional superconductors close to the phase transition in zero magnetic field

    Författare :Kateryna Medvedyeva; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik; superconductor; two dimensions; phase transition; vortex; currentvoltage characteristics; complex conductivity; scaling; critical exponents; XY-type models; dynamics; Physics; Fysik; fysik; Physics;

    Sammanfattning : The main focus of this thesis lies on the critical properties of twodimensional (2D) superconductors in zero magnetic field. Simulations based on variants of the 2D XY model are shown to give characteristic features close to the phase transition which agree qualitatively with experimental data. LÄS MER

  5. 4. A Matter of Disorder : Monte Carlo Simulations of Phase Transitions in Strongly Disordered Systems

    Författare :Marios Nikolaou; Mats Wallin; Asle Sudbø; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; phase transitions; disorder; Monte Carlo simulations; superconductivity; Statistical physics; Statistisk fysik;

    Sammanfattning : Phase transitions and their critical scaling properties, especially in systems with disorder, are important both for our theoretical understanding of our environment, but also for their practical use in applications and materials in our everyday life. This thesis presents results from finite size scaling analysis of critical phenomena in systems with disorder, using high-precision Monte Carlo simulations and state of the art numerical methods. LÄS MER

  7. 5. Experimental and Numerical Investigations of Ultra-Cold Atoms

    Författare :Magnus Rehn; Anders Kastberg; Claude Dion; Matti Kaivola; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ultracold atoms; optical lattices; Bose-Einstein condensation; quantum phase transitions; Physics; Fysik;

    Sammanfattning : I have been one of the main responsible for building a new laboratory for Bose-Einstein condensation with 87Rb. In particular, the experimental setup has been designed for performing experiments with Bose-Einstein condensates load into optical lattices of variable geometries. All parts essential for Bose-Einstein condensation are in place. LÄS MER