Hyperspectral imaging of exciton confinement within a moiré unit cell with a subnanometer electron probe

Autor: Sandhya Susarla, Mit H. Naik, Daria D. Blach, Jonas Zipfel, Takashi Taniguchi, Kenji Watanabe, Libai Huang, Ramamoorthy Ramesh, Felipe H. da Jornada, Steven G. Louie, Peter Ercius, Archana Raja
Rok vydání: 2022
Předmět:
Zdroj: Science. 378:1235-1239
ISSN: 1095-9203
0036-8075
Popis: Electronic and optical excitations in two-dimensional systems are distinctly sensitive to the presence of a moiré superlattice. We used cryogenic transmission electron microscopy and spectroscopy to simultaneously image the structural reconstruction and associated localization of the lowest-energy intralayer exciton in a rotationally aligned WS 2 -WSe 2 moiré superlattice. In conjunction with optical spectroscopy and ab initio calculations, we determined that the exciton center-of-mass wave function is confined to a radius of approximately 2 nanometers around the highest-energy stacking site in the moiré unit cell. Our results provide direct evidence that atomic reconstructions lead to the strongly confining moiré potentials and that engineering strain at the nanoscale will enable new types of excitonic lattices.
Databáze: OpenAIRE
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