Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 71: Poster Session: Graphene / Topological Insulators / Interfaces and Surfaces

HL 71.4: Poster

Mittwoch, 28. März 2012, 16:00–19:00, Poster D

Landau level splitting in monolayer and bilayer graphene superlattices — •George Pal, Walter Apel, and Ludwig Schweitzer — Physikalisch-Technische Bundesanstalt (PTB), Bundesalee 100, 38116 Braunschweig, Germany

The application of periodic potentials to graphene tailors its electronic and transport properties in a unique way, leading to novel features and interesting physics. We employ a lattice model to investigate the Landau level spectrum of graphene in perpendicular magnetic fields and an additional one-dimensional superlattice made of square potential barriers. When the potential barriers are oriented along the arm-chair direction of graphene, we find for strong magnetic fields that the zeroth Landau level of both monolayer and bilayer graphene splits into two well separated sublevels. This splitting occurs only when the superlattice barrier width is smaller than the magnetic length. In this situation, which persists even in the presence of disorder, a plateau with zero Hall conductivity is supposed to be observed around the Dirac point. The splitting occurs also in the presence of truly two-dimensional (chess-board type) superlattices, and it remains robust even in the presence of additional on-site disorder. The superlattice induced Landau level splitting is a true lattice effect that cannot be obtained from the usual continuum Dirac-fermion model of graphene. [1] G. Pal, W. Apel, and L. Schweitzer, submitted (2011)