Peierls-like phase transitions in domain walls

In this paper, we give an example how domain walls (DW) within an adsorbed monolayer form one-dimensional localized electronic states. We investigated in detail the Ag 3 × 3 phase on Si (111), a prototype system for a low dimensional electron gas, by means of scanning tunneling microscopy. The doubling of the periodicity along the DW-direction at low temperatures (80 K) suggests a metal–insulator transition of Peierls type. The superimposed intensity modulation in the direction across the DW can be interpreted in terms of lateral quantum well states. However, the simultaneous vanishing of both features at room temperature indicates more complicated changes in band structure and/or wave functions during the transition than described by the simple Peierls model.