Abstract
We have studied the incommensurate moire structure of epitaxial graphene grown on iridium(111) by dynamic low-energy electron diffraction [LEED I(V)] and noncontact atomic force microscopy (AFM) with a CO-terminated tip. Our LEED I(V) results yield the average positions of all the atoms in the surface unit cell and are in qualitative agreement with the structure obtained from density functional theory. The AFM experiments reveal local variations of the moire structure: The corrugation varies smoothly over several moire unit cells between 42 and 56 pm. We attribute these variations to the varying registry between the moire symmetry sites and the underlying substrate. We also observe isolated outliers, where the moire top sites can be offset by an additional 10 pm. This study demonstrates that AFM imaging can be used to directly yield the local surface topography with pm accuracy even on incommensurate two-dimensional structures with varying chemical reactivity.
Original language | English |
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Article number | 201406 |
Number of pages | 6 |
Journal | Physical review. B, Condensed matter and materials physics |
Volume | 88 |
Issue number | 20 |
DOIs | |
Publication status | Published - 22 Nov 2013 |
Funding
We thank A. P. Seitsonen and C. Busse for discussions. This research was supported by the Finnish Academy of Science and Letters, the Academy of Finland (Centre of Excellence in Low Temperature Quantum Phenomena and Devices No. 250280 and Project No. 218186), the European Research Council (ERC-2011-StG No. 278698 "PRECISE-NANO"), and FOM [Control over Functional Nanoparticle Solids (FNPS)]. We acknowledge the computational resources provided by Finland's IT Center for Science (CSC). This research made use of the Aalto Nanomicroscopy Center (Aalto NMC) facilities.
Keywords
- SCANNING-TUNNELING-MICROSCOPY
- HEXAGONAL BORON-NITRIDE
- DECOMPOSITION
- SUPERLATTICES
- SPECTROSCOPY
- NANOMESH
- RU(0001)
- STM