Abstract
Scanning-tunneling microscopy and density-functional theory have been employed to identify the spatial correlation between an oxygen vacancy and the associated ion pair in a defective film. The two ions can occupy different cationic shells around the vacancy. The resulting variation in the chemical environment leads to a splitting of the filled levels, which is detected with STM spectroscopy. The position of the ion pair is reflected in characteristic defect patterns observed in empty-state STM images, which arise from the bright appearance of ions next to the defect while the remain dark. Both findings demonstrate that at least one excess electron localizes in a Ce ion that is not adjacent to the O vacancy.
- Received 5 January 2011
DOI:https://doi.org/10.1103/PhysRevLett.106.246801
© 2011 American Physical Society