Manipulation of gold single crystal islands on hopg surface with a STM tip

It is demonstrated that nanometer-sized gold single crystal islands or even clusters of the islands, which were formed by deposition of gold onto an air-cleaved highly oriented pyrolytic graphite (HOPG) surface, can be manipulated on the surface in a controllable manner with the tip of a scanning tunneling microscope when the tunneling conductance is set to a large value. Since the tip does not disturb the islands if the tunneling conductance is small enough, even the islands are repeatedly scanned over by the tip, the results of the manipulation can thus be imaged with the same tip. The mechanism of the manipulation is suggested to be that at large tunneling conductance a metallic cohesive force may form between the tip and islands and may exceed the frictional force between the islands and the HOPG surface.