Flat band properties of twisted transition metal dichalcogenide homo- and heterobilayers of MoS2, MoSe2, WS2 and WSe2

Twisted bilayers of two-dimensional materials, such as twisted bilayer graphene, often feature flat electronic bands that enable the observation of electron correlation effects. In this work, we study the electronic structure of twisted transition metal dichalcogenide homo- and heterobilayers that are obtained by combining MoS2, WS2, MoSe2 and WSe2 monolayers, and show how flat band properties depend on the chemical composition of the bilayer as well as its twist angle. We determine the relaxed atomic structure of the twisted bilayers using classical force fields and calculate the electronic band structure using a tight-binding model parametrized from first-principles density-functional theory. We find that the highest valence bands in these systems can derive either from Gamma-point or K/ K'

Automated summary

This study focuses on the electronic structure of twisted transition metal dichalcogenide homo- and heterobilayers, exploring the flat band properties and revealing the correlation between chemical composition, twist angle, and electronic band structure. Classical force fields were used to determine the relaxed atomic structure of the twisted bilayers, while a tight-binding model parameterized from first-principles density-functional theory was employed to calculate the electronic band structure. The highest valence bands in these systems were found to originate from either Gamma-point or K/K'.