The structural stability of single-layer steps on (001)-(2 x 1) surfaces was studied under conditions where a static electric field was applied in the [110] direction. A 1-dimensional tight-binding model, which took account of dimer-bond and dangling-bond states on this surface, was used to analyze the situation. It was found that, when the electric field exceeded a critical value, dimer structures which were near to the step edges were appreciably weakened by the creation of soliton-like states. The 2-band nature of the surface states produced an asymmetrical instability, of the step edges, which depended upon the field direction. The results were used to explain experimental observations of a switching of the (2 x 1)/(1 x 2) domains of mono-layered vicinal (001) surfaces during direct-current heating.

T.Miyazaki, M.Fujita: Journal of Physics - Condensed Matter, 1992, 4[31], 6539-48