TIP-ASSISTED DIFFUSION ON AG(110) IN SCANNING-TUNNELING-MICROSCOPY

The influence of the tip in a scanning tunneling microscope on the ato mic motion of Ag on Ag(110) is investigated at T = 50 and 295 K. At T = 50 K the tip can move single Ag atoms preferentially along [1(1) ove r bar0$] via an attractive interaction. At T = 295 K, the tip can disp lace monatomic steps over distances as large as several hundred Angstr om. The structures thus created decay on a time scale of minutes. In c ontrast to prevailing assumptions significant tip-induced disturbances of the equilibrium shape of steps are observed even at sub-nA tunneli ng currents.