One-Dimensional Periodic Buckling at a Symmetry-Incompatible Heterointerface of the NaCl(001) Monolayer on Ir(111)

Abstract

Monolayer and multilayer NaCl(001) films are grown on an Ir(111) substrate, and strain relaxation modes are investigated by scanning tunneling microscopy (STM) and density functional theory calculations. We report that monolayer NaCl(001) exhibits an apparent one-dimensional periodic buckling along the [010] direction, which separates one-dimensional domains of pristine lattices. An atomic model of the monolayer NaCl(001)-(2 × 6) lattice on an Ir(111)-(4 × 7 3 ) substrate is proposed, and related simulation reproduces all the STM features. The calculations suggest that the 4–6 symmetry incompatibility of the NaCl(001)/Ir(111) interface leads to the formation of domain boundaries with alternately arranged top-sited and bridge-sited adatom lines along [100], resulting in one-dimensional atomic buckling. We also observe that the atomic buckling is veiled as the NaCl(001) increases to bilayer and above, suggesting that this relaxation mode is finely tuned by the crystal thickness.

Modulation of Carbon Nanotube Electronic Structure by Grain Boundary Defects in RbI on Au(111)

“…For the wide GBD, our results show a pair of states (localized at the edges of the defect, A 2 in Figure d) that are 0.4 V lower in energy than for the pristine state (in agreement with the energy difference of 0.2 V in experimental STS) and a state localized at the center of the defect (A 1 in Figure d) which is 0.6 V lower in energy than for the pristine state (in agreement with the energy difference of 0.4 V in experimental STS). Overall, the theoretically calculated LDOS at the GBD is in agreement with previous results for similar defects in NaCl on Ir(111), where atoms at the defect were shown to have, in general, downshifted LDOS . The quantitative agreement of results shown in Figure with experimental data (Figure ) thus suggests that the electronic states observed in experiment are downshifted due to the stabilizing electrostatic potential of the GBD.…”

“…Overall, the theoretically calculated LDOS at the GBD is in agreement with previous results for similar defects in NaCl on Ir(111), where atoms at the defect were shown to have, in general, downshifted LDOS. 48 The quantitative agreement of results shown in Figure 5 with experimental data (Figure 3) thus suggests that the electronic states observed in experiment are downshifted due to the stabilizing electrostatic potential of the GBD. Finally, we return to the impact of these GBDs on the electronic structure of the adsorbed SWCNT.…”

“…To optimize the GBD structure, we added individual RbI molecules to the region between the pristine RbI phases. This approach follows that of previous calculations for GBDs in NaCl on Ir(111), where NaCl molecules bridge the region between discontinuous pristine domains . In the case of the narrow defect region, the addition of a single RbI molecule ensures that each Rb (iodine) atom is adjacent to three iodine (Rb) atoms (Figure b).…”

“…This approach follows that of previous calculations for GBDs in NaCl on Ir(111), where NaCl molecules bridge the region between discontinuous pristine domains. 48 In the case of the narrow defect region, the addition of a single RbI molecule ensures that each Rb (iodine) atom is adjacent to three iodine (Rb) atoms (Figure 4b). For the case of the wide defect region, the addition of three RbI molecules with alternating orientation accomplishes the same result (Figure S5b).…”