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Growth of Co on Cu(111): subsurface growth of trilayer Co islands

1997; Elsevier BV; Volume: 387; Issue: 1-3 Linguagem: Inglês

10.1016/s0039-6028(97)00270-7

1879-2758

M.Ø. Pedersen, Ilva A. Bönicke, Erik Lægsgaard, I. Stensgaard, A. V. Ruban, Jens K. Nørskov, Flemming Besenbacher,

Catalytic Processes in Materials Science

The growth of cobalt on Cu(111) has been studied using a variable-temperature scanning tunneling microscope (STM). At a deposition temperature of 150 K, one observes the growth of three-layer Co islands with one subsurface layer. The Co islands are surrounded by a brim of Cu. The distinction between Co and Cu is made by adsorption of CO which adsorbs only on Co at room temperature, resulting in a Co(111)-(√3 × √3)R30°-CO structure. After heating the surface, or depositing Co at higher temperatures, the Cu brims gradually disappear, and vacancy islands form in the Cu(111) surface. The top-layer CoCu composition changes slowly at room temperature with Co being replaced by Cu on a timescale of ∼ 1 h, consistent with earlier ion-scattering studies. The experimental findings are in accordance with ab-initio total-energy calculations showing the thermodynamically stable island configuration to be several cobalt layers capped with one copper layer.