Diffusive and subdiffusive step dynamics

The dynamics of steps on crystal surfaces is considered. In general, the meandering of the steps obeys a subdiffusive behaviour. The characteristic asymptotic time laws depend on the microscopic mechanism for detachment and attachment of the atoms at the steps. The three limiting cases of step-edge diffusion, evaporation-condensation and terrace diffusion are studied in the framework of Langevin descriptions and by Monte Carlo simulations.