Ultraviolet absorption spectrum of the half-filled bilayer graphene | Vardan Apinyan

Summary :
⁣We consider the optical properties of the half-filled AB-stacked bilayer graphene with the excitonic pairing and condensation between the layers. Both intra and interlayer local Coulomb interaction effects have been taken into account and the role of the exact Fermi energy has been discussed in details. We have calculated the absorption coefficient, refractive index, dielectric response functions and the electron energy loss spectrum for different interlayer Coulomb interaction regimes and for different temperatures. Considering the full four-band model for the interacting AB bilayer graphene, a good agreement is achieved with other theoretical and experimental works on the subject, in particular, limiting cases of the theory. The calculations, presented here, permit to estimate accurately the effects of excitonic pairing and condensation on the optical properties of the bilayer graphene. The modifications of the plasmon excitation spectrum are discussed in details for a very large interval of the interlayer interaction parameter.


About Author :
⁣Dr. Vardan Apinyan was graduated from the Faculty of Physics at the Yerevan State University. After obtaining his Master in physics he continued his PhD research in the International Max Planck Research School in Dresden/Wrocław under the supervision of Dr. Prof. hab. Tadeusz Kopeć. Starting from December 2012, he works at the Institute of Low Temperature and Structure Research (ILTSR) in Wrocław, in the department of Condensed Matter Theory. The main research interests are the related to the study of excitonic properties in the graphene-based materials and heterostructures.