Twist-tailoring Coulomb correlations in van der Waals homobilayers
Journal article, 2020

The recent discovery of artificial phase transitions induced by stacking monolayer materials at magic twist angles represents a paradigm shift for solid state physics. Twist-induced changes of the single-particle band structure have been studied extensively, yet a precise understanding of the underlying Coulomb correlations has remained challenging. Here we reveal in experiment and theory, how the twist angle alone affects the Coulomb-induced internal structure and mutual interactions of excitons. In homobilayers of WSe2, we trace the internal 1s–2p resonance of excitons with phase-locked mid-infrared pulses as a function of the twist angle. Remarkably, the exciton binding energy is renormalized by up to a factor of two, their lifetime exhibits an enhancement by more than an order of magnitude, and the exciton-exciton interaction is widely tunable. Our work opens the possibility of tailoring quasiparticles in search of unexplored phases of matter in a broad range of van der Waals heterostructures.

Author

Philipp Merkl

University of Regensburg

F. Mooshammer

University of Regensburg

Samuel Brem

Chalmers, Physics, Condensed Matter and Materials Theory

Anna Girnghuber

University of Regensburg

Kai Qiang Lin

University of Regensburg

Leonard Weigl

University of Regensburg

Marlene Liebich

University of Regensburg

Chaw Keong Yong

University of Regensburg

Roland Gillen

University of Erlangen-Nuremberg (FAU)

Janina Maultzsch

University of Erlangen-Nuremberg (FAU)

J. M. Lupton

University of Regensburg

Ermin Malic

2D-Tech

Chalmers, Physics, Condensed Matter and Materials Theory

R. Huber

University of Regensburg

Nature Communications

2041-1723 (ISSN)

Vol. 11 1 2167

Exciton dynamics in atomically thin materials

Swedish Research Council (VR), 2019-01-01 -- 2024-12-31.

Graphene Core Project 3 (Graphene Flagship)

European Commission (EC), 2020-04-01 -- 2023-03-31.

Subject Categories

Physical Chemistry

Atom and Molecular Physics and Optics

Condensed Matter Physics

DOI

10.1038/s41467-020-16069-z

More information

Latest update

9/7/2020 7