Fig. 2: Independence on the defect’s nature and position.
From: Experimental evidence of the topological obstruction in twisted bilayer graphene
a Experimental local density of states measured from the dI/dV spectroscopy with a set point of Vb = 800 mV and it = 800 pA (top). Corresponding theoretical LDOS (Bottom). The different spectra were measured at the locations indicated by a star of the same color in Fig. 1b. b–g STM images simulated from tight-binding calculations of the QPI signal in the surface layer near a defect (top) and its Fourier transform (bottom). The scale bar is 10 nm in the real space and 1 nm−1 in reciprocal space images. The labels indicate the type of defect, its position (see Fig. 1e), and the presence or absence of heterostrain. In (b–f), the defect is modeled by a Gaussian potential of depth 1.5 eV and width σ = 1.5a0 (a0 is graphene’s lattice constant). In (g), the defect is a non-reconstructed carbon vacancy located in the top layer. The intensity of Fourier transforms is normalized to ease comparison, but the signal from the vacancy is much smaller (see Fig. S3). All the results are displayed for an energy 175 meV below the van Hove singularity, as in the measurement of Fig. 1c.
