Basics of graphene and twisted bilayer graphene

1. Twisted Bilayer Graphene
Ipsita Mandal

2. What is Graphene ?
Graphite ☛ most stable form of carbon under standard
conditions
Graphene ☛ one atom thick layer of graphite

3. Properties of Graphene ?
●
Thinnest known material ☛ about 0.345 nm
●
Strongest known material: 100 times stronger than steel &
stiffer than diamond
●
Conducts electricity 10^6 times more than copper
●
Conducts heat better than diamond
●
Most stretchable (elastic) crystal ☛ upto 20% of its initial length
●
Almost transparent but so dense that even helium cannot pass
through

4. Conductivity of Graphene
Graphene’s electrons can move easily with miniscule energy
requirement due to vanishing gap between valence &
conduction bands

5. Making Graphene:
Exfoliation

6. Nobel Prize
Nobel Prize in Physics for 2010 to
Andre Geim
&
Konstantin Novoselov
"for groundbreaking experiments regarding the
two-dimensional material graphene"

7. Twisted Bilayer Graphene
Moiré pattern obtained from
2 graphene layers
overlaid with
a relative twist angle θ

8. Magic Angle
●
2 misaligned sheets of graphene can be easily converted from
being an insulator to a superconductor
●
Could lead to the development of materials with a range of
engineered electronic properties
[ Pablo Jarillo-Herrero et al, Nature, 2018 ]
We want to investigate the theoretical reason for such
behaviour