Quantitative determination of atomic buckling of silicene by atomic force microscopy

Abstract

The atomic buckling in 2D “Xenes” (such as silicene) fosters a plethora of exotic electronic properties such as a quantum spin Hall effect and could be engineered by external strain. Quantifying the buckling magnitude with subangstrom precision is, however, challenging, since epitaxially grown 2D layers exhibit complex restructurings coexisting on the surface. Here, we characterize using low-temperature (5 K) atomic force microscopy (AFM) with CO-terminated tips assisted by density functional theory (DFT) the structure and local symmetry of each prototypical silicene phase on Ag(111) as well as extended defects. Using force spectroscopy, we directly quantify the atomic buckling of these phases within 0.1-Å precision, obtaining corrugations in the 0.8- to 1.1-Å range. The derived band structures further confirm the absence of Dirac cones in any of the silicene phases due to the strong Ag-Si hybridization. Our method paves the way for future atomic-scale analysis of the interplay between structural and electronic properties in other emerging 2D Xenes.

Majorana fermions in magnetic chains

“…We also note that such spin helices have been indeed observed in other 1D-atomic system by STM measurements [66,67,68,69]. variations in single molecules within ∼ 0.05Å precision [73,74]. As a result, the atomic buckling of ∼ 0.65Å along the triple zig-zag chain should be easily reflected in the AFM images, which instead, show flat and linear atomic chains ( Fig.…”

On‐Surface Synthesis of Nitrogen‐Doped Kagome Graphene

“…In comparison to the debrominated TBQP molecules that always lie flat, twisted PZQ bridges in the N‐KG (Figure 1 d and black arrow in Figure 2 d) are systematically observed using the high vertical precision of AFM measurements [31] . This suggests a substantial mechanical stress in the Kagome structure as a result of polymerization [28, 32] …”

Topographic signatures and manipulations of Fe atoms, CO molecules and NaCl islands on superconducting Pb(111)

“…CO dosing on the cold substrate was done in the microscope chamber by increasing the pressure via a leak valve up to p ≈ 1×10 −7 mbar for one minute. This leads to a surface coverage of about 0.1-0.3 monolayer, as we readily observed on noble metals such as Cu, Ag or Au [33,45]. Iron adatoms were evaporated in the microscope head on the substrate at a temperature below 15 K. NaCl was evaporated from a quartz crucible on samples kept at room temperature in the preparation chamber.…”