Creep and thermal rounding close to the elastic depinning threshold

KOLTON A B; PURRELLO V H; JAGLA E A; IGUAIN J L

Brunico/Bruneck

Workshop; Fundamental Problems in Statistical Physics XIV; 2017

We study the slow stochastic dynamics near the depinning threshold of an elastic interface in a random medium by solving a particularly suited model of hopping interacting particles which belongs to the quenched-Edwards-Wilkinson depinning universality class. The model allows us to compare the cases of uniformly activated and Arrhenius activated hops. In the former case, the velocity accurately follows a standard scaling law of the force and noise intensity with the analog of the thermal rounding exponent satisfying a modified ?hyperscaling? relation. For the Arrhenius activation, we find, both numerically and analytically, that the standard scaling form fails for any value of the thermal rounding exponent. We propose an alternative scaling incorporating logarithmic corrections that appropriately fit the numerical results. We argue that this anomalous scaling is related to the strong correlation between activated hops which, alternated with deterministic depinning-like avalanches, occur below the depinning threshold. We rationalize this spatio-temporal patterns by making an analogy of the present model in the near threshold creep regime with some well known models with extremal dynamics, particularly the Bak-Sneppen model.