High-temperature study of the Schwoebel effect in Au(111)

We investigate the adatom descent from straight steps on Au(111) by molecular-dynamics simulations. Au is modeled using many-body tight-binding potentials. Adatom descent may take place by a jump or by exchange; the static energy barriers are very similar for both mechanisms and much higher than the barrier for coming back to the inner terrace. However, the simulations at high temperatures (450-650 K) show that adatoms exchange fast and jumps are rare at both steps. These results suggest that the Schwoebel barriers for exchange are decreased at high temperature.