Magnetotransport Properties of Quasi-Free-Standing Epitaxial Graphene Bilayer on SiC: Evidence for Bernal Stacking

• Published in: Nano letters Vol. 11; no. 9; pp. 3624 - 3628
• Main Authors: Lee, Kayoung, Kim, Seyoung, Points, M. S, Beechem, T. E, Ohta, Taisuke, Tutuc, E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14.09.2011
• Subjects: Charge; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Graphene; Magnetic properties; Magnetic properties and materials; Magnetic properties of nanostructures; Materials science; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanostructure; Physics; Silicon carbide; Specific materials; Specific phase transitions; Stacking; Structural transitions in nanoscale materials; Structure of solids and liquids; crystallography; Temperature dependence; Transport properties; Valleys; SiC; quantum Hall; Graphene; bilayer; Bernal stacking; Temperature dependence; Epitaxial layers; Symmetry property; Stacking sequence; Atmospheric pressure; Phase transformations; Epitaxy; Silicon carbide; Magnetoresistance; Bilayers; Graphitization; Crystal structure
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl201430a

We investigate the magnetotransport properties of quasi-free-standing epitaxial graphene bilayer on SiC, grown by atmospheric pressure graphitization in Ar, followed by H2 intercalation. At the charge neutrality point, the longitudinal resistance shows an insulating behavior, which follows a temperature dependence consistent with variable range hopping transport in a gapped state. In a perpendicular magnetic field, we observe quantum Hall states (QHSs) both at filling factors (ν) multiples of four (ν = 4, 8, 12), as well as broken valley symmetry QHSs at ν = 0 and ν = 6. These results unambiguously show that the quasi-free-standing graphene bilayer grown on the Si-face of SiC exhibits Bernal stacking.