Cross-correlation functions across W(112) of current fluctuations from potassium submonolayers: Surface diffusion or soliton propagation mechanism?

Field emission current cross-correlation functions (CCFs) of flicker noise from potassium submonolayers in the tungsten (112) region are presented and discussed. They were determined for two different orientations by the two-collector technique described recently using two probes with constant distance. With increasing time delay the CCFs show a broad maximum centered at τ max. It reflects the anisotropy of the substrate and in addition τ max is Arrhenius-like temperature-and also strongly coverage-dependent. While at lower coverages surface diffusion should explain the CCF properties, a soliton or domain propagation mechanism is proposed for medium and higher coverages based on results of the adlayer soliton theory by Pokrovsky and coworkers.