Physics – Condensed Matter – Mesoscale and Nanoscale Physics
Scientific paper
2009-06-26
New J. Phys. 11 No 9 (September 2009) 095007 (22pp)
Physics
Condensed Matter
Mesoscale and Nanoscale Physics
21 pages. Figures 6 and 7 are correctly displayed in this new version
Scientific paper
10.1088/1367-2630/11/9/095007
We present exact analytical calculations of scanning tunneling currents in locally disordered graphene using a multimode description of the microscope tip. Analytical expressions for the local density of states (LDOS) are given for energies beyond the Dirac cone approximation. We show that the LDOS at the $A$ and $B$ sublattices of graphene are out of phase by $\pi$ implying that the averaged LDOS, as one moves away from the impurity, shows no trace of the $2q_F$ (with $q_F$ the Fermi momentum) Friedel modulation. This means that a STM experiment lacking atomic resolution at the sublattice level will not be able of detecting the presence of the Friedel oscillations [this seems to be the case in the experiments reported in Phys. Rev. Lett. {\bf 101}, 206802 (2008)]. The momentum maps of the LDOS for different types of impurities are given. In the case of the vacancy, $2q_F$ features are seen in these maps. In all momentum space maps, $K$ and $K+K^\prime$ features are seen. The $K+K^\prime$ features are different from what is seen around zero momentum. An interpretation for these features is given. The calculations reported here are valid for chemical substitution impurities, such as boron and nitrogen atoms, as well as for vacancies. It is shown that the density of states close to the impurity is very sensitive to type of disorder: diagonal, non-diagonal, or vacancies. In the case of weakly coupled (to the carbon atoms) impurities, the local density of states presents strong resonances at finite energies, which leads to steps in the scanning tunneling currents and to suppression of the Fano factor.
Peres Nuno. M. R.
Tsai Shan-Wen
Yang Ling
No associations
LandOfFree
Local density of states and scanning tunneling currents in graphene does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Local density of states and scanning tunneling currents in graphene, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Local density of states and scanning tunneling currents in graphene will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-670635