Anomalous scaling of the surface width during Cu electrodeposition

Kinetic roughening during thin film growth is a widely studied phenomenon, with many systems found to follow simple scaling laws. We show that for Cu electrodeposition from additive-free acid sulphate electrolyte, an extra scaling exponent is required to characterize the time evolution of the local roughness. The surface width w (l, t) scales as t(beta loc) l(H), when the deposition time t is large or the size t of the region over which w is measured is small, and as t(beta+beta loc) when I is large or t is small. This is the first report of such anomalous scaling for an experimental (2 + 1)-dimensional system. When the deposition current density or Cu concentration is varied, only beta (loc) changes, while the other power law exponents H and beta remain constant.