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Band Structures of Bilayer Graphene Superlattices

Killi, Matthew and Wu, Si and Paramekanti, Arun (2011) Band Structures of Bilayer Graphene Superlattices. In: Physical Review Letters, 107 (8).

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Official URL: http://prl.aps.org/abstract/PRL/v107/i8/e086801

Abstract

We formulate a low energy effective Hamiltonian to study superlattices in bilayer graphene (BLG) using a minimal model which supports quadratic band touching points. We show that a one dimensional (1D) periodic modulation of the chemical potential or the electric field perpendicular to the layers leads to the generation of zero-energy anisotropic massless Dirac fermions and finite energy Dirac points with tunable velocities. The electric field superlattice maps onto a coupled chain model comprised of ``topological'' edge modes. 2D superlattice modulations are shown to lead to gaps on the mini-Brillouin zone boundary but do not, for certain symmetries, gap out the quadratic band touching point. Such potential variations, induced by impurities and rippling in biased BLG, could lead to subgap modes which are argued to be relevant to understanding transport measurements.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to The American Physical Society.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 03 Sep 2011 10:26
Last Modified: 03 Sep 2011 10:26
URI: http://eprints.iisc.ernet.in/id/eprint/40409

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