Structure Transformation of the C Defects Observed at Low Temperature (80 K)

The dynamical characteristics of the C defect at low temperature (80 K) were studied by sequential scanning tunneling microscopy observations. We found that the C defect frequently transforms into a another type of defect termed as the C2 LT defect. In addition, the reversal C2 LT to C defect structural transformation was observed which implies that the C2 LT defect is a metastable state of the C defect. The observed structural transformation was completely different from that observed at room temperature. We interpret that structural transformation associated with a change in the phase of the defect is suppressed at low temperatures because it disturbs the ordering of the surrounding buckled dimers.