Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 97: Focus Session: SrTiO3: A Versatile Material from Bulk Quantum Paraelectric to 2D Superconductor II (joint session TT/KFM/MA/O)
O 97.10: Vortrag
Donnerstag, 21. März 2024, 17:30–17:45, H 0104
Quasiparticle and excitonic properties of monolayer SrTiO3 — •Lorenzo Varrassi1, Peitao Liu2, and Cesare Franchini1,3 — 1Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna — 2Shenyang National Laboratory for Materials Science, Institute of Metal Research — 3University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna.
Recently, a breakthrough has been achieved with the synthesis of free-standing SrTiO3 ultrathin films down to the monolayer limit[1]; its optical and excitonic properties remain however largely unexplored. This talk will provide insights on the quasiparticle and excitonic properties of monolayer SrTiO3, employing many-body perturbation theory.
Our analysis[2] emphasizes the need to go beyond the diagonal GW approximation and include off-diagonal self-energy elements in order to obtain correct description of the orbital hybridizations. A fully satisfying description is achieved by treating non-locality in both exchange and correlation.
The optical properties are studied through the solution of the Bethe-Salpeter equation. We observe a significant enhancement of the excitonic effects with respect to the bulk phase, with a binding energy at the optical gap about four times greater. Furthermore, the two-dimensional polarizability at the long wavelength limit is dominated by two strongly bound excitonic peaks; their character is determined through the analysis of the excitonic wavefunctions.
[1] D. Ji et al., Nature 570 (2019) 87
[2] L. Varrassi et al., arxive:2303.14830 (2023)