Revealing the topological phase diagrams of 2D heterostructures using SIESTA

ELTE

Zoltán Tajkov

Kick-off meeting 2024.09.26

outline

siesta

Powerful DFT tool utilizing localized basis set. This means it provides a tight-binding Hamiltonian. Also models open-boundary systems.

bitei / graphene

Mechanical strain induces topological phase transition in graphene / bitei heterostructures

zrte5

Using the SIESTA code we were able to clear out the confusion around the peculiar properties of ZrTe5

SIESTA

Capabilities

  • Total and partial energies.
  • Atomic forces.
  • Geometry relaxation, fixed or variable cell.
  • Spin polarized calculations (collinear or not).
  • Local and orbital-projected density of states.
  • Band structure.
  • Model open-boundary systems (TRANS-SIESTA)

Standard DFT stuff

SIESTA

Capabilities

Model open-boundary systems (TRANS-SIESTA)

Standard DFT stuff

SIESTA

Capabilities

Model open-boundary systems (TRANS-SIESTA)

Standard DFT stuff

outline

siesta

Powerful DFT tool utilizing localized basis set. This means it provides a tight-binding Hamiltonian. Also models open-boundary systems.

bitei / graphene

Mechanical strain induce topological phase transition in graphene / bitei heterostructures

zrte5

Using the SIESTA code we were able to clear out the confusion around the peculiar properties of ZrTe5

bitei / graphene systems

BiTeI sandwich: Kou et al. ACS Nano, 8 10448 (2014)

Z. Tajkov et al. Nanoscale 11, 12704 (2019)

bitei / graphene systems

BiTeI sandwich: Kou et al. ACS Nano, 8 10448 (2014)

Z. Tajkov et al. Nanoscale 11, 12704 (2019)

bitei / graphene systems

Z. Tajkov et al. Nanoscale 11, 12704 (2019)

Tini-Tiny

trivial gap

bitei / graphene systems

Z. Tajkov et al. Nanoscale 11, 12704 (2019)

Not so tiny

topological gap

in-plane strain

Tini-Tiny

trivial gap

bitei / graphene systems

Z. Tajkov et al. Appl. Sci. 2019, 9(20), 4330

bitei / graphene systems

Z. Tajkov et al. Appl. Sci. 2019, 9(20), 4330

Tight-binding level

outline

siesta

Powerful DFT tool utilizing localized basis set. This means it provides a tight-binding Hamiltonian. Also models open-boundary systems.

bitei / graphene

Mechanical strain induce topological phase transition in graphene / bitei heterostructures

zrte5

Using the SIESTA code we were able to clear out the confusion around the peculiar properties of ZrTe5

zrte5

zrte5

zrte5

$$ \#1 $$

$$ \#2 $$

$$ d $$

$$ h$$

$$ R_1 $$

$$ R_2 $$

$$ Ang $$

55

49

1015

813

178

90

6000

4560

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)

zrte5

COMSOL and DFT

zrte5

Ab initio

zrte5

Monolayer

zrte5

Bilayer

Phase diagrams

USING

SIESTA

Correlated states on the Hill

HUN-REN Centre for Energy Research

Capabilities in 2D

  • Corralated states
  • Topological states
  • Small angle moiré

PEOPLE

Péter Nemes-Incze

Levente Tapasztó

Péter Vancsó