Abstract
Atomically resolved elevated-temperature scanning tunneling microscope (STM) images of (001) cobalt and nickel monoxide surfaces obtained under similar conditions show an order of magnitude difference in the atomic corrugation heights. Surface-electronic structure calculations taking into account the Hubbard U term show that on the CoO (001) surface the lowest unoccupied state has character as compared with the predominantly lowest empty state on NiO (001). The difference in the symmetry of unoccupied d orbitals on CoO (001) and NiO (001) surfaces is responsible for the much lower level of atomic contrast observed in the STM images of cobalt oxide.
- Received 23 November 1998
DOI:https://doi.org/10.1103/PhysRevB.59.7342
©1999 American Physical Society