Topological Exciton Bands in Moiré Heterojunctions

Moiré patterns are common in van der Waals heterostructures and can be used to apply periodic potentials to elementary excitations. We show that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moiré patterns that introduce twist-angle...

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Bibliographic Details
Published in:Physical review letters 2017-04, Vol.118 (14), p.147401-147401, Article 147401
Main Authors: Wu, Fengcheng, Lovorn, Timothy, MacDonald, A H
Format: Article
Language:English
Subjects:
Exchange
Excitation spectra
Heterojunctions
MATERIALS SCIENCE
Moire patterns
Satellites
Topology
Transition metals
Valleys
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Summary:Moiré patterns are common in van der Waals heterostructures and can be used to apply periodic potentials to elementary excitations. We show that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moiré patterns that introduce twist-angle dependent satellite excitonic peaks. Topological exciton bands with nonzero Chern numbers that support chiral excitonic edge states can be engineered by combining three ingredients: (i) the valley Berry phase induced by electron-hole exchange interactions, (ii) the moiré potential, and (iii) the valley Zeeman field.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.118.147401