Twist-angle dependent dehybridization of momentum-indirect excitons in MoSe2/MoS2 heterostructures

Abstract

The moiré superlattice has emerged as a powerful way to tune excitonic properties in two-dimensional van der Waals structures. However, the current understanding of the influence of the twist angle for interlayer excitons (IXs) in heterostructures is mainly limited to momentum-direct K–K transitions. In this work, we use a judicious combination of spectroscopy and many-particle theory to investigate the influence of the twist angle on momentum-indirect IXs of a MoSe2/MoS2 heterostructure. Here, the energetically lowest state is a dark and strongly hybridized ΓK exciton. We show that increasing the twist angle from an aligned structure (0∘ or 60∘) gives rise to a large blue shift of the IX, which is a manifestation of the strong dehybridization of this state. Moreover, for small twist angle heterostructures, our photoluminescence measurements reveal contributions from two IX states, which our modelling attributes to transitions from different moiré minibands. Our finding contributes to a better fundamental understanding of the influence of the moiré pattern on the hybridization of momentum-dark IX states, which may be important for applications in moiré-tronics including novel quantum technologies.