Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Superconductivity: Mechanisms, Phase Diagram, Competing Order

TT 29.12: Vortrag

Donnerstag, 28. Februar 2008, 12:45–13:00, H 3010

Surface superconductivity and capacitance of superconductors under electric and magnetic fields — •Klaus Morawetz^1,2, Pavel Lipavsky^3,4, Jan Kolacek⁴, Ernst Helmut Brandt⁵, and Michael Schreiber¹ — ¹Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany — ²Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden, Germany — ³Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 12116 Prague 2, Czech Republic — ⁴Institute of Physics, Academy of Sciences, Cukrovarnická 10, 16253 Prague 6, Czech Republic — ⁵Max Planck Institute for Metals Research, 70506 Stuttgart, Germany

A superconducting layer exposed to a perpendicular electric and parallel magnetic field is considered within the Ginzburg-Landau (GL) approach. The GL equation is solved near the surface and the surface energy is calculated. The nucleation critical field is shown to be changed in dependence on the magnetic and electric field. Special consideration is payed to the induced magnetic-field effect caused by diamagnetic surface currents. The latter effect constitutes the main contribution to the effective inverse capacitance which determines the effective penetration depth. The surface energy becomes strongly dependent on the width of the sample. An experimental realization is suggested for determining the change in the effective capacitance of the layer.