Correlated insulating states at fractional fillings of the WS2/WSe2 moiré lattice

• Published in: Nature physics Vol. 17; no. 6; pp. 715 - 719
• Main Authors: Huang, Xiong, Wang, Tianmeng, Miao, Shengnan, Wang, Chong, Li, Zhipeng, Lian, Zhen, Taniguchi, Takashi, Watanabe, Kenji, Okamoto, Satoshi, Xiao, Di, Shi, Su-Fei, Cui, Yong-Tao
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2021; Nature Publishing Group; Nature Publishing Group (NPG)
• Subjects: 639/301/357/1018; 639/766/119/995; Atomic; Bilayers; Classical and Continuum Physics; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Complex Systems; Condensed Matter Physics; Electrons; Engineering; Graphene; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Letter; MATERIALS SCIENCE; Mathematical and Computational Physics; Molecular; Optical and Plasma Physics; Physics; Physics and Astronomy; Superlattices; Theoretical; Transition metal compounds; Tungsten disulfide; Unit cell
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/s41567-021-01171-w

The strong electron interactions in the minibands formed in moiré superlattices of van der Waals materials, such as twisted graphene and transition metal dichalcogenides, make such systems a fascinating platform with which to study strongly correlated states 1 – 19 . In most systems, the correlated states appear when the moiré lattice is filled by an integer number of electrons per moiré unit cell. Recently, correlated states at fractional fillings of 1/3 and 2/3 holes per moiré unit cell have been reported in the WS 2 /WSe 2 hetero-bilayer, hinting at the long-range nature of the electron interaction 16 . Here we observe a series of correlated insulating states at fractional fillings of the moiré minibands on both electron- and hole-doped sides in angle-aligned WS 2 /WSe 2 hetero-bilayers, with certain states persisting at temperatures up to 120 K. Simulations reveal that these insulating states correspond to ordering of electrons in the moiré lattice with a periodicity much larger than the moiré unit cell, indicating a surprisingly strong and long-range interaction beyond the nearest neighbours. Twisted bilayers of WS 2 and WSe 2 have correlated states that correspond to real-space ordering of the electrons on a length scale much longer than the moiré pattern.