Electromigration of single metal atoms observed by scanning tunneling microscopy

The authors show in this letter that single metal atoms on a Ni(111) surface can be pushed by electromigration forces from a scanning tunneling microscope tip. This repulsive interaction is obsd. over a length scale of 6 nm. While for voltages above -300 mV the atoms are pulled by the microscope tip, the atoms are pushed away below this threshold. This migration is explained by a resonant scattering of strongly correlated electrons. At small voltages chem. forces are pulling the atom, while for larger voltages the at. manipulation is assisted by the tunneling current. [on SciFinder (R)