Ultrafast switching of trions in 2D materials by terahertz photons – Publication by B9 (Malic) in Nature Photonics

In a joint study including the experimental group of  Alexey Chernikov (TU Dresden), Manfred Helm and Stephan Winnerl (Helmholtz Zentrum Dresden-Rossendorf) as well as the theoretical group of Ermin Malic (Philipps-Universität Marburg),the ultrafast switching of trions in 2D materials were investigated by terahertz photons.

External control of optical excitations is crucial for manipulating light–matter coupling and is highly desirable for photonic technologies. Excitons in monolayer semiconductors emerged as a unique nanoscale platform in this context, offering strong light–matter coupling, spin–valley locking and exceptional tunability. Importantly, they allow electrical switching of their optical response due to efficient interactions of excitonic emitters with free charge carriers, forming new quasiparticles known as trions and Fermi polarons. Due to major limitations of how fast the light emission of these states can be tuned, the majority of applications are restricted to an essentially static regime.

Here, the groups of Ermin Malic, Alexey Chernikov as well as Manfred Helm and Stephan Winnerl demonstrate switching of excitonic light emitters in monolayer semiconductors on ultrafast picosecond time scales by applying short pulses in the terahertz spectral range following optical injection. The process is based on a rapid conversion of trions to excitons by absorption of terahertz photons inducing photodetachment. The required resonance conditions as well as the demonstration of the tunability of the process with delay time and terahertz pulse power were achieved by monitoring time-resolved emission dynamics in optical-pump/terahertz-push experiments.

The results introduce a versatile experimental tool for fundamental research of light-emitting excitations of composite Bose–Fermi mixtures and open up pathways towards technological developments of new types of nanophotonic device based on atomically thin materials.

Publication

T. Venanzi, M. Cuccu, R. Perea-Causin, X. Sun, S. Brem, D. Erkensten, T. Taniguchi, K. Watanabe, Ermin Malic, M. Helm, S. Winnerl, A. Chernikov
Ultrafast switching of trions in 2D materials by terahertz photons
Nat. Photon. (2024) DOI:10.1038/s41566-024-01512-0

Contact

Prof. Dr. Ermin Malic
Philipps-Universität Marburg
SFB 1083 project B9
Tel.: 06421 28-22640
EMAIL