We investigated a local Au atomic diffusion on an Au(111) surface by using a scanning tunneling microscope (STM). The diffusion, which was dependent on a tip material, was triggered by an applied voltage pulse. Using an Au tip, small one-dimensional atomic diffusion was observed during the tip scan around a position where a voltage pulse was applied. As the result, finger-like stripes grew at a step along the [1-21] direction of the Au(111) surface. In case of a Pt-Ir tip, large two-dimensional atomic diffusion was observed on the scanned area of the Au(111) surface. Movable Au atoms around the position where voltage pulse was applied were swept by the tip scan with field gradient effect.
