Seminar presentation
At the group meeting of the
Centre of Low Temperature Physics
Zoltán Tajkov
2022.09.29
Manipulating the topological properties of thin heterostructures
TOPICS
Graphene
Competition of trivial and topological phases in graphene based hybrid systems
ZrTe5
Revealing the topological phase diagram of ZrTe using the complex strain fields of microbubbles
Competing gapped and gapless ground state in the flat surface band of multilayer rhombohedral graphite
Graphite
BiTeX/graphene heterostructures
BiTeI sandwich: Kou et al. ACS Nano, 8 10448 (2014)
BiTeX/graphene heterostructures
Z. Tajkov et al. Nanoscale 11, 12704 (2019)
DFT (SIESTA) results
topological
trivial
Sandwich:
~40 meV topological gap
One sided:
~1 meV trivial gap
BiTeX/graphene heterostructures
Z. Tajkov et al. Nanoscale 11, 12704 (2019)
topological
trivial
BiTeX/graphene heterostructures
Z. Tajkov et al. Nanoscale 11, 12704 (2019)
The most important parameters
Kekulé
Kane-Mele
Strain promotes SOC \( \rightarrow \) TI
topological
trivial
BiTeX/graphene heterostructures
Strain can close the gap at \(\boldsymbol{k}=\boldsymbol{0}\) if
Gamayun et al. New J. Phys. 20, 023016 (2018)
Z. Tajkov et. al. Physical Review B 101 (23), 235146 (2020)
Zirconium pentatelluride - ZrTe5
Mutch, J., Chen, et. al. Science Advances, 2019 5(8).
Zirconium pentatelluride - ZrTe5
Mutch, J., Chen, et. al. Science Advances, 2019 5(8).
Zirconium pentatelluride - ZrTe5
$$ \#1 $$
$$ \#2 $$
$$ d $$
$$ h$$
$$ R_1 $$
$$ R_2 $$
$$ Ang $$
55
49
1015
813
178
90
6000
4560
Zirconium pentatelluride - ZrTe5
$$ O_x $$
$$ \mathcal{A}_1 $$
$$ \mathcal{B}_1 $$
$$ C $$
$$ O_z$$
$$ O_x $$
$$ \mathcal{A}_1 $$
$$ \mathcal{B}_1 $$
$$ C $$
$$ O_z$$
Stiffness tensor (DFT)
Finite Element Method
Electric properties (DFT)
Zirconium pentatelluride - ZrTe5
COMSOL and DFT
Zirconium pentatelluride - ZrTe5
Ab initio
Zirconium pentatelluride - ZrTe5
Ab initio - Mono and bilayer
Rhombohedral Graphite
SSH chain
Rhombohedral Graphite
What does the experiment say? STM results
Rhombohedral Graphite
DMRG - Beyond meanfield
Theory
Degenerate ground state!
Rhombohedral Graphite
Experiments
Minimal
By novidad21
Minimal
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