Dielectric Engineering of Electronic Correlations in a van der Waals Heterostructure
Journal article, 2018

Heterostructures of van der Waals bonded layered materials offer unique means to tailor dielectric screening with atomic-layer precision, opening a fertile field of fundamental research. The optical analyses used so far have relied on interband spectroscopy. Here we demonstrate how a capping layer of hexagonal boron nitride (hBN) renormalizes the internal structure of excitons in a WSe 2 monolayer using intraband transitions. Ultrabroadband terahertz probes sensitively map out the full complex-valued mid-infrared conductivity of the heterostructure after optical injection of 1s A excitons. This approach allows us to trace the energies and line widths of the atom-like 1s-2p transition of optically bright and dark excitons as well as the densities of these quasiparticles. The excitonic resonance red shifts and narrows in the WSe 2 /hBN heterostructure compared to the bare monolayer. Furthermore, the ultrafast temporal evolution of the mid-infrared response function evidences the formation of optically dark excitons from an initial bright population. Our results provide key insight into the effect of nonlocal screening on electron-hole correlations and open new possibilities of dielectric engineering of van der Waals heterostructures.

atomically thin 2D crystals

dark excitons

van der Waals heterostructures

dielectric engineering



Philipp Steinleitner

University of Regensburg

Philipp Merkl

University of Regensburg

Alexander Graf

University of Regensburg

P. Nagler

University of Regensburg

Kenji Watanabe

National Institute for Materials Science (NIMS)

Takashi Taniguchi

National Institute for Materials Science (NIMS)

Jonas Zipfel

University of Regensburg

C. Schuller

University of Regensburg

T. Korn

University of Regensburg

A. Chernikov

University of Regensburg

Samuel Brem

Chalmers, Physics, Condensed Matter Theory

M. Selig

Technische Universität Berlin

Gunnar Berghäuser

Chalmers, Physics, Condensed Matter Theory

Ermin Malic

Chalmers, Physics, Condensed Matter Theory

Rupert Huber

University of Regensburg

Nano Letters

1530-6984 (ISSN) 1530-6992 (eISSN)

Vol. 18 2 1402-1409

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics



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