Seminarium Fizyki Politechniki Wrocławskiej
PWr, bud. A1, sala 322
Exciton many-body processes and population dynamics in 2D semiconductors
Prof. Stefano Dal Conte
Department of Physics, Politecnico di Milano
Monolayers of Transition Metal Dichalcogenides (TMDs) have become a central focus in condensed matter physics research due to their exceptional optoelectronic properties, which arise from strong light-matter interactions. Quantum confinement and reduced Coulomb screening make TMDs an ideal system for studying excitons (i.e. ground state and excited state excitons) and their many-body complexes (i.e. trions, biexcitons, and other multiparticle states), as well as exploring their tunability in response to external factors like electric and magnetic fields, or lattice strain [1]. Furthermore, the ability to optically control and manipulate the spin/valley degree of freedom has significantly amplified interest in these materials [2]. The possibility to stack two or more TMD layers and form vertical 2D heterostructures hosting long-lived interlayer excitons further enrich the excitons physics of these materials [3].
Since the advent of 2D materials, out-of-equilibrium spectroscopies have been extensively used to study the mechanisms of formation, relaxation, and recombination of excitons occurring on different timescales, ranging from tens of femtoseconds to nanoseconds.
Here, I will exploit helicity resolved broadband pump-probe optical spectroscopy to study valley-resolved exciton dynamics in monolayers TMD focusing on intervalley coupling dynamics between excitons, valley depolarization mechanisms [4] and inter/intravalley biexcitons [5]. The second part of the talk will be devoted to the study of exciton/carrier dynamics in TMD heterobilayers focusing on the formation process of interlayer excitons [6].
[1] T. Mueller and E. Malic npj 2D mater. appl. 2, 29 (2018)
[2] K. F. Mak, D. Xiao and J. Shan Nat. Photonics 12, 451–460 (2018)
[3] Y. Jiang, S. Chen, W. Zheng, B. Zheng and Anlian Pan Light sci. appl. 10, 72 (2021)
[4] O. Dogadov et al. submitted
[5] T. Deckert et al. submitted
[6] V. Policht et al. Nat Commun. 14, 7273 (2023)
