Hybridized intervalley moiré excitons and flat bands in twisted WSe(2)bilayers
Journal article, 2020

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 WSe(2)bilayers. In particular, we show that the strong hybridization of electrons at the ? point leads to a drastic redshift of the momentum-dark K-? exciton, accompanied by the emergence of flat moire 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 moire potential of the twisted bilayer lattice.

Author

Samuel Brem

Chalmers, Physics, Condensed Matter and Materials Theory

Kai-Qiang Lin

University of Regensburg

Roland Gillen

University of Erlangen-Nuremberg (FAU)

Jonas M. Bauer

University of Regensburg

Janina Maultzsch

University of Erlangen-Nuremberg (FAU)

John M. Lupton

University of Regensburg

Ermin Malic

Chalmers, Physics, Condensed Matter and Materials Theory

Nanoscale

2040-3364 (ISSN)

Vol. 12 20 11088-11094

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics

DOI

10.1039/d0nr02160a

PubMed

32400821

More information

Latest update

10/12/2020