Suppression of Quasiparticle Scattering Signals in Bilayer Graphene Due to Layer Polarization and Destructive Interference

Abstract

We study chemically gated bilayer graphene using scanning tunneling microscopy and spectroscopy complemented by tight-binding calculations. Gating is achieved by intercalating Cs between bilayer graphene and Ir(111), thereby shifting the conduction band minima below the chemical potential. Scattering between electronic states (both intraband and interband) is detected via quasiparticle interference. However, not all expected processes are visible in our experiment. We uncover two general effects causing this suppression: first, intercalation leads to an asymmetrical distribution of the states within the two layers, which significantly reduces the scanning tunneling spectroscopy signal of standing waves mainly present in the lower layer; second, forward scattering processes, connecting points on the constant energy contours with parallel velocities, do not produce pronounced standing waves due to destructive interference. We present a theory to describe the interference signal for a general n-band material.

Massive and massless charge carriers in an epitaxially strained alkali metal quantum well on graphene

“…Figure 1c depicts an ARPES scan of bilayer graphene/Ir(111) which shows two π bands (labels π 1 and π 2 ) instead of one π band which is observed for monolayer graphene/Ir(111). The two observed parabolic π valence bands are consistent with Bernal (or AB) stacking 40 and in agreement with earlier reports on bilayer graphene on Ir(111) 14 . An equi-energy cut around the K point at a binding energy E B = 0.7 eV is shown in Fig.…”

“…1a, b is significantly reduced by Cs intercalation. This is evident from previous works which measured Fourier transform scanning tunneling spectroscopy on Cs-intercalated bilayer graphene 14 . We believe that the flat substrate obtained by Cs intercalation is also important for the subsequent growth of Cs films.…”

“…For cesium (Cs) adsorbed on or intercalated underneath monolayer graphene, a perfect order in a (2 × 2) or a ( ffiffi ffi 3 p ffiffi ffi 3 p )R30°superlattice has been observed 11,[14][15][16] . The interaction of epitaxial bilayer graphene with Cs has revealed that, at low Cs coverages, the energetically favorable position of Cs is below the bilayer 14 . However, the structure and the electronic properties of the large Cs coverages on bilayer graphene are completely unexplored.…”

“…In the present work we study the interaction of epitaxial bilayer graphene with high Cs coverages by performing longer Cs evaporation onto the graphene bilayer than the previous reports 11,14,15 . In these conditions, Cs intercalates under and in between the graphene bilayer and even grows on top of bilayer as a crystalline, thin Cs film.…”

Determination of the trigonal warping orientation in Bernal-stacked bilayer graphene via scanning tunneling microscopy

“…1b. 1,2,[19][20][21][22][23]4,5,11,[14][15][16][17][18] One angle-resolved photoemission study reported an orientation corresponding to Fig. 1c, 24 although the experimental resolution did not allow unambiguous determination of the low energy TW orientation.…”