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Physical review. B, 2019-07, Vol.100 (3), p.035443, Article 035443
2019
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Autor(en) / Beteiligte
Titel
Wake potential in graphene-insulator-graphene composite systems
Ist Teil von
  • Physical review. B, 2019-07, Vol.100 (3), p.035443, Article 035443
Ort / Verlag
College Park: American Physical Society
Erscheinungsjahr
2019
Quelle
APS: American Physical Society E-Journals (Physics)
Beschreibungen/Notizen
  • We study the wake potential produced by an external charged particle that moves parallel to various sy1−Al2O3−sy2 sandwich-like composites, where the system syi (with i=1,2) may be vacuum, pristine graphene, or doped graphene. The effective dielectric function of the composites is obtained using three complementary methods for graphene's electronic response, based on the massless Dirac fermions (MDF) method, the extended hydrodynamic (eHD) model, and the ab initio approach. Three velocity regimes are explored with respect to the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity vF. In the low-velocity regime (below vF), only the transverse optical (TO) phonons in the Al2O3 layer contribute to the wake potential in the surface with sy2 (which is nearest to the charged particle), in a manner that is only sensitive to the composition of that system: if sy2 is vacuum, the TO phonons give rise to intense oscillations in the wake potential, which are strongly suppressed if sy2 is pristine or doped graphene. For intermediate velocities (above vF), the hybridized plasmon–TO phonon modes on both surfaces contribute to the wake potential in the surface with sy2, with the most dominant contribution coming from the hybridized Dirac-like plasmonic modes. In the high-velocity regime (well above vF), the highest-lying hybridized Dirac plasmon gives the dominant contribution to the wake potential, which exhibits a typical V-shaped wave-front pattern that lags behind the charged particle. It is found that the MDF method agrees very well with the results of the ab initio method for small and intermediate velocities. However, in the high-velocity regime, the high-energy π plasmon in graphene introduces new features in the wake potential in the form of fast oscillations, just behind the charged particle. Those oscillations in the wake potential are well described by both the eHD and the ab initio method, proving that the π plasmon indeed behaves as a collective mode.
Sprache
Englisch
Identifikatoren
ISSN: 2469-9950
eISSN: 2469-9969
DOI: 10.1103/PhysRevB.100.035443
Titel-ID: cdi_osti_scitechconnect_22946929

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