Dielectric Engineering of Electronic Correlations in a van der Waals Heterostructure
Artikel i vetenskaplig tidskrift, 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

Dichalcogenides

Författare

Philipp Steinleitner

Universität Regensburg

Philipp Merkl

Universität Regensburg

Alexander Graf

Universität Regensburg

P. Nagler

Universität Regensburg

Kenji Watanabe

National Institute for Materials Science

Takashi Taniguchi

National Institute for Materials Science

Jonas Zipfel

Universität Regensburg

C. Schuller

Universität Regensburg

T. Korn

Universität Regensburg

A. Chernikov

Universität Regensburg

Samuel Brem

Chalmers, Fysik, Kondenserade materiens teori

M. Selig

Technische Universität Berlin

Gunnar Berghäuser

Chalmers, Fysik, Kondenserade materiens teori

Ermin Malic

Chalmers, Fysik, Kondenserade materiens teori

Rupert Huber

Universität Regensburg

Nano Letters

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

Vol. 18 1402-1409

Ämneskategorier

Atom- och molekylfysik och optik

Annan fysik

Den kondenserade materiens fysik

DOI

10.1021/acs.nanolett.7b05132