Dynamic roughening of the magnetic flux landscape in YBa2Cu3O7-x

We study the magnetic flux landscape in YBa2Cu3O7-x thin films as a two dimensional rough surface. The vortex density in the superconductor forms a self-affine structure in both space and time. It is characterized by a roughness exponent α=0.76(3) and a growth exponent β=0.57(6). The roughening is caused by flux avalanches in a self-organized critical state, which is formed in the vortex matter of the superconductor. We discuss our results in the context of other roughening systems in the presence of quenched disorder.