An atomic-scale study of the Co induced dendrite formation on Pt(111)

We have studied the initial growth of Co on the Pt(111) surface in a temperature range of 300-400 K with scanning tunneling microscopy, low energy ion scattering and Auger electron spectroscopy. In agreement with previous work by Grutter and Durig, when depositing 0.1 ML Co on Pt(111) at 400 K, the formation of large dendrites is observed. These dendrites are formed in conjunction with a Co induced local reconstruction of the Pt(111) surface, resulting in dislocations. The dendrites, however, show no evidence for any dislocations below their surface, the local reconstruction is observed to be lifted by the formation of the dendrites. LEIS data suggest that the dendrites consist mainly of Pt, implying, together with the STM data, that Co is incorporated underneath the Pt. A model for this process is proposed. (C) 1999 Elsevier Science B.V. All rights reserved.