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

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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

The International Conference on Internal Interfaces, ICII-24, was held in Marburg

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SFB 1083 organized the third International Conference on Internal Interfaces (ICII-24) in Marburg with many national and international speakers.

The meeting brought together more than 100 scientists from across the world in the new library building of the Philipps-Universität Marburg. From those, over 25 national and international speakers were invited to present their most recent progress in interface-research. Oral and poster sessions set the framework for intensive discussions on the newest developments in a fast-changing research field.

Thanks to the generous donations of Dock Chemicals and Scienta Omicron, the SFB awarded poster prizes for the best posters presented during conference. The first price was awarded to Klaus Zollner from the University of Regensburg (poster title: “Proximity-induced spin interactions in twisted van der Waals heterostructures”). The second price was shared between Dr. Sabine Wenzel (poster title: “Selective on-surface synthesis of isokekulene through strong molecule-metal interaction”) and Dr. Roberto Rosati (poster title: “Engineering the charge-transfer excitons in 2D lateral heterostructures”) both from Marburg. The committee congratulates all three award winners.

The attractive setting for the event provided by the Philipps-Universität Marburg and the city contributed to making it a memorable meeting.

For more details please check out the meeting’s homepage.

35. Erfinderlabor: Scientific curiosity of the next Generation

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Hessen’s young MINT scientists conduct research on hydrogen and renewable energies within the SFB 1083 and Philipps University Marburg

The 35th Inventors’ Lab (Erfinderlabor) of the Center for Chemistry (Zentrum für Chemie, ZFC) has successfully entered its finale. This year’s event was once again organized by the ZFC in cooperation with the Philipps University of Marburg and Elkamet and supported by other renowned cooperation partners such as the SFB 1083 and LEA (Hesse State Energy Agency).

The practice-oriented workshop not only offers valuable career orientation on career opportunities in the MINT environment (mathematics, informatics, natural sciences and technology), but also always addresses a current topic of high socio-political and economic relevance. The focus of this year’s Inventors’ Lab was on renewable energies and hydrogen.

The participants were selected from 126 female and 111 male students from 99 Hessian schools, the German School Seoul International and the German Embassy School New Delhi. The sixteen students in four teams dealt with different issues in the context of the energy transition in different research groups, which are part of the SFB 1083. The topics were the use of TiO2 in photovoltaics, the hydrogen storage in organic molecules as well as the functioning of batteries and energy storage materials. Finally, the usage of raspberries in solar cells was investigated.

On May 17, the participants presented their research results on the topic of the energy transition to young people in the career orientation phase as well as representatives from research, business and politics at a virtual closing event. Armin Schwarz, Hessian Minister for Culture, Education and Opportunities, praised the “outstanding achievements” of the participants and described the content covered in the inventors’ lab as “directly relevant to the scientific and economic development of the state”.  Prof. Dr. Sabine Pankuweit also emphasized: “Renewable energies and hydrogen are topics that could not be more topical.” The Vice President for Equal Opportunities and Career Development at Philipps-Universität Marburg joined the virtual closing event directly from a research laboratory.

The experts were impressed by the technical curiosity and quick comprehension, but also by the motivation and team spirit of the young people. “The graphics were well designed and the results were presented scientifically correct,” said Dr. Johanna Heine from the SFB during the virtual closing event (https://www.youtube.com/watch?v=n1u0s7DYPmA).

The local project partner was the Chemikum Marburg represented by Dr. Christof Wegscheid-Gerlach. “The Inventors’ Lab exemplifies how scientific topics of the future can be communicated at the intersection of school and university, and thus how both levels of education can be interlinked.”

Contact

Dr. Christof Wegscheid-Gerlach
Philipps-Universität Marburg
SFB 1083 project Oe
Tel.: 06421 28-25843
EMAIL