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 T-c superconductivity, magnetic order, or charge density wave order. Here we demonstrate that rhombohedral multilayers are easily obtained by epitaxial growth on 3C-S1C(111) on a 2 degrees 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.
Evidence for Flat Bands near the Fermi Level in Epitaxial Rhombohedral Multilayer Graphene / Pierucci, Debora; Sediri, Haikel; Hajlaoui, Mahdi; Girard, Jean Christophe; Brumme, Thomas; Calandra, Matteo; Velez Fort, Emilio; Patriarche, Gilles; Silly, Mathieu G.; Ferro, Gabriel; Souliere, Veronique; Marangolo, Massimiliano; Sirotti, Fausto; Mauri, Francesco; Ouerghi, Abdelkarim. - In: ACS NANO. - ISSN 1936-0851. - 9:5(2015), pp. 5432-5439. [10.1021/acsnano.5b01239]
Evidence for Flat Bands near the Fermi Level in Epitaxial Rhombohedral Multilayer Graphene
MAURI, FRANCESCO;
2015
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 T-c superconductivity, magnetic order, or charge density wave order. Here we demonstrate that rhombohedral multilayers are easily obtained by epitaxial growth on 3C-S1C(111) on a 2 degrees 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
