Abstract
Penetration of magnetic flux in YBa2Cu3O7 superconducting thin films in an external magnetic field is visualized using a magneto-optic technique. A variety of flux patterns due to non-linear vortex diffusion is observed: (1) Roughening of the flux front with scaling exponents identical to those observed in burning paper including two distinct regimes where respectively spatial disorder and temporal disorder dominate. In the latter regime Kardar-Parisi-Zhang behavior is found. (2) Fractal penetration of flux with Hausdorff dimension depending on the critical current anisotropy. (3) Penetration as 'flux-rivers'. (4) The occurrence of commensurate and incommensurate channels in films with anti-dots as predicted in numerical simulations by Reichhardt, Olson and Nori. It is shown that most of the observed behavior is related to the non-linear diffusion of vortices by comparison with simulations of the non-linear diffusion equation appropiate for vortices.
| Original language | English |
|---|---|
| Pages (from-to) | 1011-1014 |
| Number of pages | 4 |
| Journal | Physica C: Superconductivity and its Applications |
| Volume | 341-348 |
| Issue number | PART 3 |
| DOIs | |
| Publication status | Published - 2000 |
Bibliographical note
Funding Information:In conclusion, we have found a whole range of interesting patterns which develop during flux penetration in thin films with various microstructure. Remarkably, from X-Ray scattering we find that films with the best epitaxy show the clearest roughening and that with decreasing epitaxy the flux penetration becomes smoother. Furthermore we have found that the superconducting vortex system is an ideal system to study roughening phenomena, a.o. because the experiments are repeatable, unlike experiments on paper or on porous media. This work is part of the research program of the Stichting Fundamenteel Onderzoek der Ma-terie (FOM), which is financially supported by the Nederlandse Organisatie voor Wetenschap-pelijk Onderzoek (NWO).