Evidence for Flat Bands near the Fermi Level in Epitaxial Rhombohedral Multilayer Graphene

Abstract

The stacking order of multilayer graphene has a profound influence on its electronic properties. In particular, it has been predicted that a rhombohedral stacking sequence displays a very flat conducting surface state: the longer the sequence, the flatter the band. In such a flat band, the role of electron-electron correlation is enhanced, possibly resulting in high Tc superconductivity, magnetic order, or charge density wave order. Here we demonstrate that rhombohedral multilayers are easily obtained by epitaxial growth on 3C-SiC(111) on a 2° off-axis 6H-SiC(0001). The resulting samples contain rhombohedral sequences of five layers on 70% of the surface. We confirm the presence of the flat band at the Fermi level by scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy, in close agreement with the predictions of density functional theory calculations.

Rhombohedral Multilayer Graphene: A Magneto-Raman Scattering Study

“…23−25 Experimental signatures of these flat bands has been recently observed in scanning tunnelling spectroscopy (STS) and angular-resolved photo emission spectroscopy (ARPES) investigations of nanometer scale domains of ABC-stacked graphene multilayers (5 layers) grown on 3C-SiC. 26 In this Letter, we demonstrate, using Raman scattering techniques, that ABC-stacked multilayers (N > 5) can be found within exfoliated N-LG flakes. They have characteristic signatures in their Raman scattering response, which allow for their identification at room temperature.…”

Nexus and Dirac lines in topological materials

“…The projection of the spiral to the top or bottom surface of graphite determines the boundary of the (approximate) surface flat band [8,9]. This flattening of the spectrum has been recently observed in epitaxial rhombohedral multilayer graphene [11].…”

Peeling of multilayer graphene creates complex interlayer sliding patterns

“…This view is supported be related studies that have shown explicitly that a wider unit cell inŷ-direction does not give raise to relevant additional effects 15 . In experiments multilayer graphene is not always nicely stacked and hence predicting sliding patterns in practice is difficult 25 . Moreover, we considered only cases where bending was parallel either to armchair-or to zigzagdirection.…”