Twist-tailoring Coulomb correlations in van der Waals homobilayers
Journal
Nature communications
Journal Volume
11
Journal Issue
1
Date Issued
2020-05-01
Author(s)
Merkl, Philipp
Mooshammer, Fabian
Brem, Samuel
Girnghuber, Anna
Lin, Kai-Qiang
Weigl, Leonard
Liebich, Marlene
Gillen, Roland
Maultzsch, Janina
Lupton, John M
Malic, Ermin
Huber, Rupert
Abstract
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.
Subjects
INDIRECT INTERLAYER EXCITONS; BANDGAP RENORMALIZATION; MOMENTUM; VALLEY; SPIN
Publisher
NATURE PUBLISHING GROUP
Type
journal article