Europhys. Lett.
Volume 61, Number 4, February 2003
Page(s) 473 - 479
Section General
Published online 01 February 2003
DOI: 10.1209/epl/i2003-00153-2
Europhys. Lett., 61 (4) , pp. 473-479 (2003)

Structural similarity between the magnetic-flux profile in superconductors and the surface of a 2d rice pile

M. S. Welling, C. M. Aegerter and R. J. Wijngaarden

Division of Physics and Astronomy, Vrije Universiteit De Boelelaan 1081, 1081HV Amsterdam, The Netherlands

(Received 31 May 2002; accepted in final form 4 December 2002)

We analyze the magnetic-flux profile in the critical state of an $\chem{YBa_2Cu_3O}$ 7-x thin film. It is found that the profile forms a self-affine structure in both space and time. Furthermore, the surface of a pile of rice is studied, which also shows a self-affine structure. These experimental results are compared to simulations of a two-dimensional version of the Oslo model for sandpiles. The exponents characterizing the roughness and dynamics of the profiles for both experimental systems agree with each other, the values being $\alpha = 0.39(3)$ for the roughness exponents and $\beta = 0.50(3)$ for the growth exponents. These values are reproduced in the simulations as well. This shows that a simple sandpile model can be used to describe the shape and dynamics of the vortex landscape in the critical state. Conversely, superconductors may be used as a model granular system.

05.65.+b - Self-organized systems.
45.70.Vn - Granular models of complex systems; traffic flow.
74.60.Ge - Flux pinning, flux creep, and flux-line lattice dynamics.

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