Observation of Exciton Redshift-Blueshift Crossover in Monolayer WS<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 28621953.
- Also identified by DOI 10.1021/acs.nanolett.7b01034.
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Abstract
We report a rare atom-like interaction between excitons in monolayer WS<sub>2</sub>, 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 interparticle interaction, which holds promise to pursue the predicted liquid and crystalline phases of excitons in two-dimensional materials.