Imaging moir\'e flat bands in 3D reconstructed WSe2/WS2 superlattices
Abstract
Moir\'e superlattices in transition metal dichalcogenide (TMD) heterostructures can host novel correlated quantum phenomena due to the interplay of narrow moir\'e flat bands and strong, long-range Coulomb interactions1-5. However, microscopic knowledge of the atomically-reconstructed moir\'e superlattice and resulting flat bands is still lacking, which is critical for fundamental understanding and control of the correlated moir\'e phenomena. Here we quantitatively study the moir\'e flat bands in three-dimensional (3D) reconstructed WSe2/WS2 moir\'e superlattices by comparing scanning tunneling spectroscopy (STS) of high quality exfoliated TMD heterostructure devices with ab initio simulations of TMD moir\'e superlattices. A strong 3D buckling reconstruction accompanied by large in-plane strain redistribution is identified in our WSe2/WS2 moir\'e heterostructures. STS imaging demonstrates that this results in a remarkably narrow and highly localized K-point moir\'e flat band at the valence band edge of the heterostructure. A series of moir\'e flat bands are observed at different energies that exhibit varying degrees of localization. Our observations contradict previous simplified theoretical models but agree quantitatively with ab initio simulations that fully capture the 3D structural reconstruction. Here the strain redistribution and 3D buckling dominate the effective moir\'e potential and result in moir\'e flat bands at the Brillouin zone K points.
Cite
@article{arxiv.2007.06113,
title = {Imaging moir\'e flat bands in 3D reconstructed WSe2/WS2 superlattices},
author = {Hongyuan Li and Shaowei Li and Mit H. Naik and Jingxu Xie and Xinyu Li and Jiayin Wang and Emma Regan and Danqing Wang and Wenyu Zhao and Sihan Zhao and Salman Kahn and Kentaro Yumigeta and Mark Blei and Takashi Taniguchi and Kenji Watanabe and Sefaattin Tongay and Alex Zettl and Steven G. Louie and Feng Wang and Michael F. Crommie},
journal= {arXiv preprint arXiv:2007.06113},
year = {2021}
}