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TT: Fachverband Tiefe Temperaturen

TT 3: Topology: Quantum Hall Systems

TT 3.10: Vortrag

Montag, 18. März 2024, 12:15–12:30, H 2053

Thermal robustness of the quantum spin Hall phase in monolayer WTe₂ from single-point first-principles simulations — •Antimo Marrazzo — Dipartimento di Fisica, Università di Trieste, Strada Costiera 11, Trieste I-34151, Italy

I will present first-principles simulations of the temperature effects on the electronic structure of monolayer 1T’-WTe₂ and consider the contributions of both thermal expansion and electron-phonon coupling [1]. First, I will show that thermal expansion is weak but tends to increase the indirect band gap. Then, I will discuss the effect of electron-phonon coupling on the band structure, which has been calculated with nonperturbative methods, observing a small reduction of the band inversion with increasing temperature. Notably, the topological phase and the presence of a finite gap are found to be particularly robust to thermal effects up to and above room temperature. Finally, I will introduce a single-point formula to calculate Z₂ topological invariants in the supercell framework [2], where a single Hamiltonian diagonalisation is performed. Beyond disordered systems, our approach [2] is particularly useful to investigate the role of defects, to study topological alloys and in the context of ab initio molecular dynamics simulations at finite temperature.

[1] A. Marrazzo, Phys. Rev. Materials 7 (2023) L021201

2] R. Favata, A. Marrazzo, Electron. Struct. 5 (2023) 014005

Keywords: Topological insulators; temperature; electron-phonon coupling; first-principles simulations; 2D materials