Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers

Brem S, Lin KQ, Gillen R, Bauer JM, Maultzsch J, Lupton JM, Malic E (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Nanoscale Royal Society of Chemistry

Book Volume: 12

Pages Range: 11088-11094

Journal Issue: 20

DOI: 10.1039/d0nr02160a

Abstract

The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent hybridization of excitonic states. In this joint theory-experiment study, we demonstrate the impact of interlayer hybridization on bright and momentum-dark excitons in twisted WSe2 bilayers. In particular, we show that the strong hybridization of electrons at the Λ point leads to a drastic redshift of the momentum-dark K-Λ exciton, accompanied by the emergence of flat moiré exciton bands at small twist angles. We directly compare theoretically predicted and experimentally measured optical spectra allowing us to identify photoluminescence signals stemming from phonon-assisted recombination of layer-hybridized dark excitons. Moreover, we predict the emergence of additional spectral features resulting from the moiré potential of the twisted bilayer lattice.

Authors with CRIS profile

Roland Gillen Lehrstuhl für Experimentalphysik Janina Maultzsch Lehrstuhl für Experimentalphysik

Involved external institutions

Universität Regensburg DE Germany (DE) Chalmers University of Technology / Chalmers tekniska högskola SE Sweden (SE)

How to cite

APA:

Brem, S., Lin, K.Q., Gillen, R., Bauer, J.M., Maultzsch, J., Lupton, J.M., & Malic, E. (2020). Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers. Nanoscale, 12(20), 11088-11094. https://doi.org/10.1039/d0nr02160a

MLA:

Brem, Samuel, et al. "Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers." Nanoscale 12.20 (2020): 11088-11094.

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