Lateral manipulation of single Cu atoms on flat and stepped copper surfaces

We demonstrate that single Cu atoms can be pulled in single hops across stepped and flat Cu surfaces at low temperatures using a scanning tunneling microscope. By recording the tip height at constant current during manipulation the hopping length and the position of the tip apex relative to the substrate lattice, at which a hop is induced, can be measured. By this way it is possible to resolve that a Cu atom moves during manipulation on Cu(lll) along [1 (1) over bar 0]-depending on the chosen gap resistance-either by long hops from one fee adsite to the next or by shea hops while intermediately occupying hcp sites. On the "stepped" Cu(211)-surface hops between adjacent fivefold adsites can be observed during manipulation along [0 (1) over bar 1]. (C) 1998 American Vacuum Society. [S0734-2101(98)07303-5].