Interface dynamics at the depinning transition

We study the local scaling properties of driven interfaces in disordered media modeled by the Edwards-Wilkinson equation with quenched noise. We find that, due to the super-rough character of the interface close to the depinning transition, the local width exhibits an anomalous temporal scaling. It does not saturate at a characteristic time $t_s(l) \sim l^z$ as expected, but suffers an anomalous temporal crossover to a different time regime $t^{\beta_*}$, where $\beta_* \simeq 0.21$. This is associated with the existence of a local roughness exponent $\alpha_{loc} \simeq 1$ that differs from the global one $\alpha \simeq 1.2$. The relevance of the typical size of pinned sites regions near the critical point is investigated and the definition of the critical depinning is dicussed.