Numerical calculation of the Casimir-Polder interaction between a graphene sheet with vacancies and an atom

T. P. Cysne, T. G. Rappoport, Aires Ferreira, J. M. Viana Parente Lopes, and N. M. R. Peres
Phys. Rev. B 94, 235405 – Published 5 December 2016

Abstract

In this work the Casimir-Polder interaction energy between a rubidium atom and a disordered graphene sheet is investigated beyond the Dirac cone approximation by means of accurate real-space tight-binding calculations. As a model of defected graphene, we consider a tight-binding model of π electrons on a honeycomb lattice with a small concentration of vacancies. The optical response of the graphene sheet is evaluated with full spectral resolution by means of exact Chebyshev polynomial expansions of the Kubo formula in large lattices in excess of 10 million atoms. At low temperatures, the optical response of defected graphene is found to display two qualitatively distinct behaviors with a clear transition around finite (nonzero) Fermi energy. In the vicinity of the Dirac point, the imaginary part of optical conductivity is negative for low frequencies while the real part is strongly suppressed. On the other hand, for high doping, it has the same features found in the Drude model within the Dirac cone approximation, namely, a Drude peak at small frequencies and a change of sign in the imaginary part above the interband threshold. These characteristics translate into a nonmonotonic behavior of the Casimir-Polder interaction energy with very small variation with doping in the vicinity of the neutrality point while having the same form of the interaction calculated with Drude's model at high electronic density.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 26 August 2016
  • Revised 22 October 2016

DOI:https://doi.org/10.1103/PhysRevB.94.235405

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied PhysicsAtomic, Molecular & Optical

Authors & Affiliations

T. P. Cysne and T. G. Rappoport

  • Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro 21941-972, Rio de Janeiro, Brazil

Aires Ferreira

  • Department of Physics, University of York, York YO10 5DD, United Kingdom

J. M. Viana Parente Lopes

  • Centro de Fisica and Departamento de Fisica, Universidade do Minho, Campus de Gualtar, Braga 4710-057, Portugal, and Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal

N. M. R. Peres

  • Centro de Fisica and Departamento de Fisica, Universidade do Minho, Campus de Gualtar, Braga 4710-057, Portugal

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 94, Iss. 23 — 15 December 2016

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×