Non-Arrhenius growth behavior, bilayer and reentrant layer growth for ultrathin Co films on Cu(0 0 1)

Grazing scattering of 25 keV He atoms is applied to study island nucleation and growth of Co on Cu(0 0 1) in real time and real space. With decreasing growth temperature, we observe, starting at 470 K, step-flow growth, layer growth, bilayer growth and, below 210 K, reentrant layer growth. The density of nucleated islands shows a complex 'N-shaped' dependence on temperature, which is at variance with standard nucleation theory. Results are explained on the basis of recent density-functional calculations