Electronic Structure Theory of Weakly Interacting Bilayers
Abstract:
With the advances in nano-science and technology, quantum materials are
promising platforms beyond the current silicon industry. The challenges with these
next-generation materials include the characterizations and manipulations of the new
quantum phases and excitations, and the theoretical modeling. Since the successful
exfoliation of the two-dimensional graphene layers, the layered materials as a new
category of nano-materials are under extensive investigations. More materials such as
transition metal dichalcogenides are discovered in this type. Due to its layered
geometry and various physics properties, these layered materials are suitable to study
the interplay between different physics by stacking them together with the stacking
order and the orientations as the control knobs. However, as a crucial element to
understand the interaction between layers, the accurate and transferable interlayer
coupling across layers are lacking. In most cases, either large scale density
functional theory calculations are carried out or empirical forms for the potential
are used in the simulations. In our work, we mapped out these interlayer interactions
based on ab-initio Wannier transformation, using graphene-graphene and graphene-
hexagonal boron nitride interfaces as the examples. We further perform simulations for
twisted bilayer graphene and compare with the experiments carried out in Jarillo-
Herrero group at MIT. The electronic structure under magnetic field (~8.5T) is also
investigated. This establishes the ab-initio Wannier tight-binding approach as an
efficient and reliable method applicable to the more general van der Waals
heterostructures.
promising platforms beyond the current silicon industry. The challenges with these
next-generation materials include the characterizations and manipulations of the new
quantum phases and excitations, and the theoretical modeling. Since the successful
exfoliation of the two-dimensional graphene layers, the layered materials as a new
category of nano-materials are under extensive investigations. More materials such as
transition metal dichalcogenides are discovered in this type. Due to its layered
geometry and various physics properties, these layered materials are suitable to study
the interplay between different physics by stacking them together with the stacking
order and the orientations as the control knobs. However, as a crucial element to
understand the interaction between layers, the accurate and transferable interlayer
coupling across layers are lacking. In most cases, either large scale density
functional theory calculations are carried out or empirical forms for the potential
are used in the simulations. In our work, we mapped out these interlayer interactions
based on ab-initio Wannier transformation, using graphene-graphene and graphene-
hexagonal boron nitride interfaces as the examples. We further perform simulations for
twisted bilayer graphene and compare with the experiments carried out in Jarillo-
Herrero group at MIT. The electronic structure under magnetic field (~8.5T) is also
investigated. This establishes the ab-initio Wannier tight-binding approach as an
efficient and reliable method applicable to the more general van der Waals
heterostructures.
