Mechanical strain induced topological phase transition in ZrTe5
Topological Quantum Computing Group, BME, 2021.07.26.
Zoltán Tajkov,
ELTE, Department of Biological Physics
Nanostructures Department, Centre for Energy Research
ZrTe5
ZrTe5
What is so interesting?
- Weak / strong TI ?
- Sensitive to structural changes
- Literature is inconsistent
Own measurements
ZrTe5
Own measurements
ZrTe5
DFT results I.: Stiffness Tensor
Hooke's law: \( \sigma_{ij}=C_{ijkl}\varepsilon_{kl} \)
\( \boldsymbol{C} \): stiffness tensor, 81 number, 36 independent
Orthorombic, 9 parameters
Free energy:
F=\frac{1}{2}\lambda_{xxxx}u^2_{xx}+\frac{1}{2}\lambda_{yyyy}u^2_{yy}+\frac{1}{2}\lambda_{zzzz}u^2_{zz}+\lambda_{xxyy}u_{xx}u_{yy} + \\
+\lambda_{xxzz}u_{xx}u_{zz} +\lambda_{yyzz}u_{yy}u_{zz}+2\lambda_{xyxy}u_{xy}^2+2\lambda_{xzxz}u_{xz}^2+2\lambda_{yzyz}u_{yz}^2
ZrTe5
DFT results II.: Phase diagram
WTI
STI
ZrTe5
DFT results III.: Bubble strain pattern
Insensitive
Gap closing - opening
ZrTe5
Where are we on the map?
Molecular Dynamics Simulation
Continuum mechanics
FEM
COMSOL
ZrTe5
To-do
- DFT Mapping
- COMSOL
Special thanks to
Péter Nemes-Incze
Dániel Nagy
László Oroszlány
János Koltai
