Flip motion of heterogeneous buckled dimers on Ge(0 0 1) by electron injection from STM tip

Surface motion of a topological defect between p (2 × 2) and c (4 × 2) structures, a "kink", across buckled Sn-Ge and Si-Ge dimers on Ge(0 0 1) surfaces was investigated using scanning tunneling microscopy. Energy thresholds of π^* electrons for flipping these dimers in the kink are obtained by analyzing the kink surface motion. Electronic states of these systems and energy barriers for flipping the dimers are examined by first-principles calculations for considering elementary processes of the electronically-excited flip motion of the dimers. We propose that the flip motion is caused by a resonant scattering of the π^* electrons with localized electronic states at the kink.