Title: Ab initio Charge Transport, Excitonic and Magneto-optical Properties of van der Waals Interfaces with Chalcogen Vacancies
When: Monday, June 05, (2023), 12:00
Place: Department of Condensed Matter Physics, Faculty of Sciences, Module 3, Seminar Room (5th Floor).
Speaker: Daniel Hernangómez Pérez, Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Israel.
Recently, there has been a significant amount of research on the charge transfer, magneto-optical, and excitonic properties of van der Waals materials. This is because these materials are crucial components in ultrathin optoelectronic, photovoltaic, and photocatalytic applications, where quasi-particles and excitons act as carriers in charge, spin, and energy transfer processes. Structural complexity, reduced dimensionality, interface composition, and the presence of impurities and adatoms can significantly affect these processes. In this presentation, I will discuss some of these complexities using first principles, focusing on transition-metal dichalcogenides (TMDC) and TMDC-graphene interfaces. Specifically, I will explore the impact of atomic-size defects on optical and magnetic properties and demonstrate how the presence of defects can lead to structurally controllable excitonic magnetic response [1-3]. I will also examine the role of symmetries in charge transfer and excitonic properties in TMDC-graphene heterobilayers with monoatomic chalcogen vacancies, analyzing the impact of subgap defect-based features on microscopic dynamics and excitonic features. Finally, I will show how defects can become a slow coherent transport channel for interlayer charge transfer  while strongly altering the exciton properties of the TMDC-graphene interface through a combination of folding, screening, and mixing of optical transitions .
- E. Mitterreiter, B. Schuler, A. Micevic, D. Hernangómez-Pérez, et al. Nat. Comm. 12, 3822 (2021).
- T. Amit, D. Hernangómez-Pérez, G. Cohen, D. Y. Qiu, and S. Refaely-Abramson, Phys. Rev. B 106, L161407 (2022).
- A. Hötger, T. Amit, J. Klein, et al. npj 2D Mater. Appl. 7, 30 (2023).
- D. Hernangómez-Pérez, A. Donarini, and S. Refaely-Abramson, Phys. Rev. B 107, 075417, Editors’ Suggestion, (2023).
- D. Hernangómez-Pérez, A. Kleiner, and S. Refaely-Abramson (arXiv:2303.13650).