학술논문
Tuning commensurability in twisted van der Waals bilayers
Document Type
article
Author
Li, Yanxing; Zhang, Fan; Ha, Viet-Anh; Lin, Yu-Chuan; Dong, Chengye; Gao, Qiang; Liu, Zhida; Liu, Xiaohui; Ryu, Sae Hee; Kim, Hyunsue; Jozwiak, Chris; Bostwick, Aaron; Watanabe, Kenji; Taniguchi, Takashi; Kousa, Bishoy; Li, Xiaoqin; Rotenberg, Eli; Khalaf, Eslam; Robinson, Joshua A; Giustino, Feliciano; Shih, Chih-Kang
Source
Nature. 625(7995)
Subject
Language
Abstract
Moiré superlattices based on van der Waals bilayers1-4 created at small twist angles lead to a long wavelength pattern with approximate translational symmetry. At large twist angles (θt), moiré patterns are, in general, incommensurate except for a few discrete angles. Here we show that large-angle twisted bilayers offer distinctly different platforms. More specifically, by using twisted tungsten diselenide bilayers, we create the incommensurate dodecagon quasicrystals at θt = 30° and the commensurate moiré crystals at θt = 21.8° and 38.2°. Valley-resolved scanning tunnelling spectroscopy shows disparate behaviours between moiré crystals (with translational symmetry) and quasicrystals (with broken translational symmetry). In particular, the K valley shows rich electronic structures exemplified by the formation of mini-gaps near the valence band maximum. These discoveries demonstrate that bilayers with large twist angles offer a design platform to explore moiré physics beyond those formed with small twist angles.