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Z. Novotny, G. Argentero, Z. Wang, M. Schmid, U. Diebold, G. Parkinson:
"Ordered Array of Single Adatoms with Remarkable Thermal Stability: Au/Fe₃O₄(001)";
Physical Review Letters, 108 (2012), 2161031 - 2161035.

Gold deposited on the Fe3O4
ð001Þ surface at room temperature was studied using scanning tunneling
microscopy (STM) and x-ray photoelectron spectroscopy (XPS). This surface forms a ð ffiffiffi
2
p
ffiffiffi
2
p
ÞR45
reconstruction, where pairs of Fe and neighboring O ions are slightly displaced laterally producing
undulating rows with ``narrow´´ and ``wide´´ hollow sites. At low coverages, single Au adatoms adsorb
exclusively at the narrow sites, with no significant sintering up to annealing temperatures of 400 C. We
propose the strong site preference to be related to charge and orbital ordering within the first subsurface
layer of Fe3O4
ð001Þ-ð ffiffiffi
2
p
ffiffiffi
2
p
ÞR45 . Because of its high thermal stability, this could prove an ideal
model system for probing the chemical reactivity of single atomic species.