Local Atomic Diffusion on Au(111) Surface Induced by Au Tip

On an Au(111) surface, Au atomic diffusion induced by a voltage pulse was demonstrated using a scanning tunneling microscope (STM) with an Au tip in air. Applying a voltage pulse as a trigger, we observed local diffusion of Au atoms around the position where the voltage pulse was applied. Upon repeating tip scanning, fingerlike stripes grew gradually from a step; the direction of the stripes was affected by the structure of the Au(111) surface and the tip-scan direction. In our experiments, movable Au atoms on the local area were swept by tip scanning via the field gradient effect. Local atomic Au diffusion could be induced since activation energy was reduced by applying the voltage pulse.