Fig. 3



Fig. 3 : 

STM measurements at T =5 K of quasiparticle interferences (QPIs) due to point defects in ML and BL graphene on SiC(0001). Data, originally analyzed using the WSXm software [70], are taken from Ref. [30]. (a) A 50×50 nm2 constant current STM image on a ML terrace. Sample bias: −4 mV. (b) A 50×50 nm2 dI /dV STM image on a BL terrace. Sample bias: −25 mV. QPIs of period 5 nm show up on BL (b), but are not detected on ML (a). (c)–(d) Two-dimensional Fourier transform of the STM images shown on (a) and (b). Image sizes: 40×40 nm−2. (e)–(g) Numerical 10×10 nm−2 zooms-in of the center of (c) and (d), with an absent (e) or present (g) ring of radius 2q F related to intravalley backscattering processes. (f)–(h) Numerical 10×10 nm−2 zooms-in of one of the six outer patterns of (c) and (d), with a split (f) or full (h) ring of radius 2q F related to intervalley scattering processes. The missing intensities (no central ring, split outer rings) found in the 2D FT of the LDOS map of ML graphene originate from the pseudospin texture, as discussed in the main text.