Propagation dynamics of exciton-electron complexes in atomically-thin semiconductors

• Applicants: Professor Dr. Alexey Chernikov; Professor Dr. Ermin Malic
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542873285

Atomically-thin layers of semiconducting transition metal dichalcogenides emerged as an excellent platform to study interacting electronic many-particle states. A particularly interesting scenario, relevant from both fundamental physics and applications perspectives, it the simultaneous presence of bound electron-hole complexes, known as excitons, and free charge carriers. The properties of these composite Bose-Fermi mixtures are a topic of intense research in these systems due to their strong impact on the optical response. However, while the physics of the resulting trion and Fermi polaron complexes are well understood in the static limit, little is known about the propagation dynamics of these states, with respect to both linear and non-linear phenomena. Moreover, recently demonstrated emergence of Wigner phases of electrons in monolayer semiconductors at experimentally accessible conditions opens up studies of a very unusual and intriguing scenario involving excitons moving through an electron crystal. This motivates the main aim of this proposal to develop a microscopic understanding of the many-particle processes determining propagation dynamics of exciton-electron complexes in atomically-thin semiconductors. The focus lies on understanding non-linear phenomena associated with the exciton-carrier mixtures as well as the impact of correlated electronic Wigner states on the exciton transport. We will combine advanced microscopic many-particle methods with transient microscopy of gate-tunable samples to monitor the behavior of excitonic complexes in the presence of free charges in time, energy, and space. Ultimately, this should allow us to address the influence of electronic correlations on the physics of exciton complexes, reaching beyond proximity screening effects into the realm of exciton dynamics and transport. We envision to offer a comprehensive picture for non-linear phenomena of mobile exciton-electron quasiparticles with pathways towards external tunability and control.

• DFG Programme: Research Grants