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arXiv · 1804.10347

Observation of exciton redshift-blueshift crossover in monolayer WS2

Edbert J. Sie·Alexander Steinhoff·Christopher Gies·Chun Hung Lui·Qiong Ma·Malte Rosner·Gunnar Schonhoff·Frank Jahnke·Tim O. Wehling·Yi-Hsien Lee·Jing Kong·Pablo Jarillo-Herrero·Nuh Gedik
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Abstract

We report a rare atom-like interaction between excitons in monolayer WS2, measured using ultrafast absorption spectroscopy. At increasing excitation density, the exciton resonance energy exhibits a pronounced redshift followed by an anomalous blueshift. Using both material-realistic computation and phenomenological modeling, we attribute this observation to plasma effects and an attraction-repulsion crossover of the exciton-exciton interaction that mimics the Lennard-Jones potential between atoms. Our experiment demonstrates a strong analogy between excitons and atoms with respect to inter-particle interaction, which holds promise to pursue the predicted liquid and crystalline phases of excitons in two-dimensional materials.

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Edbert J. Sie, Alexander Steinhoff, Christopher Gies, Chun Hung Lui, Qiong Ma, Malte Rosner, Gunnar Schonhoff, Frank Jahnke, Tim O. Wehling, Yi-Hsien Lee, Jing Kong, Pablo Jarillo-Herrero, Nuh Gedik. 2018-04-27. Observation of exciton redshift-blueshift crossover in monolayer WS2. https://doi.org/10.1021/acs.nanolett.7b01034

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