Twisted graphene bilayer around the first magic angle engineered by heterostrain

Jia Bin Qiao, Long Jing Yin, Lin He*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Citations (Scopus)

Abstract

Very recently, twisted graphene bilayers (TGBs) around the first magic angle θ≈1.1 have attracted much attention for the realization of exotic quantum states, such as correlated insulator behavior and unconventional superconductivity. Here we elaborately study a series of TGBs around the first magic angle engineered by heterostrain, where each layer is strained independently. Our experiment indicates that a moderate heterostrain enables the structural evolution from the small-angle TGB (θ ∼ 1.5°) to the strained magic-angle TGB (θ ∼ 1.1°), exhibiting the characteristic low-energy flat bands. The heterostrain can even drive the system into highly strained tiny-angle TGBs (θ 1.1°) with large deformed tetragonal superlattices, where a unique network of topological helical edge states emerges. Furthermore, the predicted domain wall modes, which are strongly localized and result in a hexagon-triangle-mixed frustrated lattice derived from the Kagome lattice, are observed in the strained tiny-angle TGBs.

Original languageEnglish
Article number235402
JournalPhysical Review B
Volume98
Issue number23
DOIs
Publication statusPublished - 3 Dec 2018
Externally publishedYes

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