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Long-range adsorbate interactions mediated by a two-dimensional electron gas

2002; American Physical Society; Volume: 65; Issue: 11 Linguagem: Inglês

10.1103/physrevb.65.115420

1095-3795

Nikolaus Knorr, Harald Brune, Maximilian Epple, Andreas Hirstein, M. Alexander Schneider, Klaus Kern,

Surface and Thin Film Phenomena

We report on long-range interactions between adsorbates on metal surfaces with a surface state. A comparison of three adsorbate/substrate systems [Cu/Cu(111), Co/Cu(111), and Co/Ag(111)] suggests the general existence of such interactions and shows up common characteristics. In all cases, the interaction energy $E(r)$ manifests itself up to a distance of 60 \AA{}, decays as ${1/r}^{2},$ and oscillates with a period of ${\ensuremath{\lambda}}_{\mathrm{F}}/2.$ Our data are in excellent agreement with theory and establish the link between the spatial variation of the interaction energy and the adsorbate scattering properties. We demonstrate that the long-range interactions stabilize an ordered two-dimensional (2D) gas of adsorbates and thus create states of dilute 2D matter.