Growth of Co on Cu(111): Temperature dependence and interlayer spacings

Helium atom scattering has been used to investigate the morphology of thin cobalt films thermally evaporated onto a copper (111) surface. We report the variation of interlayer spacing as cobalt films are grown at three different temperatures: 400 K, 300 K, and 110 K. The methodology gives interlayer spacing for the surface without recourse to specific models of the growth process. The results indicate that, for cobalt grown on copper (111) at 400 K, there is no change in the interlayer spacing up to approximately 4 monolayers. For growth at lower temperatures a dramatic contraction of the observed interlayer spacing is observed. The cobalt interlayer spacings have been measured to be 1.81 +/- 0.02 Angstrom and 1.87 +/- 0.02 Angstrom at 110 K and 300 K, respectively.