Optical properties of Bernal-stacked bilayer graphene: A theoretical study

Faris Kadi and Ermin Malic
Phys. Rev. B 89, 045419 – Published 21 January 2014

Abstract

We present a microscopic study of optical properties of Bernal-stacked bilayer graphene. Our focus lies on the absorption spectrum explicitly including the impact of fully momentum-dependent optical and Coulomb matrix elements. Our approach is based on the density matrix formalism combined with tight-binding wave functions. The energy dispersion of bilayer graphene exhibits four parabolic bands resulting in interesting optical features: We find a pronounced low-energy peak, which can be clearly ascribed to cross transitions at the Dirac point. Furthermore, the bilayer spectrum shows two energetically close absorption peaks in the ultraviolet region resulting from interband transitions at the saddle point of the Brillouin zone. We discuss the impact of the carrier-light coupling element containing the optical selection rules and determining the oscillator strength of all possible optical transitions. Furthermore, we show the influence of the Coulomb interaction accounting for a considerable overall energy renormalization and the formation of electron-hole pairs at the saddle point.

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  • Received 13 August 2013
  • Revised 22 November 2013

DOI:https://doi.org/10.1103/PhysRevB.89.045419

©2014 American Physical Society

Authors & Affiliations

Faris Kadi* and Ermin Malic

  • Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany

  • *faris.kadi@mailbox.tu-berlin.de

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Issue

Vol. 89, Iss. 4 — 15 January 2014

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