nl7b01034_si_001.pdf (3.09 MB)
Observation of Exciton Redshift–Blueshift Crossover in Monolayer WS2
journal contribution
posted on 2017-06-16, 18:24 authored by E. J. Sie, A. Steinhoff, C. Gies, C. H. Lui, Q. Ma, M. Rösner, G. Schönhoff, F. Jahnke, T. O. Wehling, Y.-H. Lee, J. Kong, P. Jarillo-Herrero, N. GedikWe
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 interparticle
interaction, which holds promise to pursue the predicted liquid and
crystalline phases of excitons in two-dimensional materials.