OLIVEIRA, N. W. S.; http://lattes.cnpq.br/3299568738135171; OLIVEIRA, Nallyson William Santos.
Resumo:
Graphene consists of a layer of carbon atoms that are compacted in network two-dimensional
hexagonal (2D). The stacking of two monolayers forms the graphene bilayer and the
realization of the rotation between the monolayers makes the appearance of the twisted
bilayer graphene, that due to promising experimental results of this system rotated to the
magic angles, the phenomenon of superconductivity was observed in 1.1
◦
, which opened
doors for further studies in 2D materials. In this work, we dedicate our studies to the
twisted bilayer graphene system with the angle of 21.8
◦ and also for the same system
intercalated with the atom of lithium, using calculations of first principles based on density
functional theory (DFT) using the method of full potential linearized augmented plane
waves (FP-LAPW), that are implemented in the WIEN2K computational package. With
the realization of the rotation, we have the Moiré pattern and we get the Moiré unit cell,
which is composed of 28 carbon atoms. To understand the electronic structure of both
materials, we calculate the densisty of states, band structure and electronic density. Our
results from the twisted bilayer graphene show us that the two Van Hove peaks around
Fermi energy, in density of state, get closer. The bands close to the Fermi energy in
the M-K direction it has a linear dispersion. When we intercalate with Li, we observe
a displacement of the Fermi energy, where it shows an electron transfer to the twisted
bilayer graphene. In conclusion, our work shows the tendency of the system to become
superconducting as the angle goes towards the magic angles.