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- Title
Abundant electric-field tunable symmetry-broken states in twisted monolayer-bilayer graphene.
- Authors
Peng, Huimin; Zhong, Jinrui; Feng, Qi; Hu, Yuqing; Li, Qiuli; Zhang, Shihao; Mao, Jinhai; Duan, Junxi; Yao, Yugui
- Abstract
Electron-electron correlations can lift the high degeneracies in strong correlated systems, resulting in various symmetry-broken states. Twisted monolayer-bilayer graphene (tMBG) is an especially rich system due to its low crystalline symmetry. Here, we report abundant electric-field tunable symmetry-broken states in tMBG. The ground state at half filling of the conduction flat band is spin- and valley-polarization dominated under positive and negative electric field, respectively, consistent with our theoretical calculations. In addition, we find a symmetry-broken Chern insulator emanating from 1.5 electrons per moiré unit with C = 3 emerges at high magnetic field in a negative electric field range. The C = 3 suggests that one and a half flavor-polarized Chern 2 bands within the same valley are filled, consistent with the valley-polarization-dominated half-filling state under negative electric field, while the fractional filling stems from a density-wave state held by enlarged unit cells containing two moiré units. Twisted monolayer-bilayer graphene has attracted intense interest due to its rich symmetry-broken states which can be tuned by an external electric field. Here, the authors determine the ground states at half-filling of the conduction band under opposite electric field and report on a symmetry-broken Chern insulator state with its Chern number closely related to the half-filling ground states.
- Subjects
UNIT cell; SYMMETRY breaking; ELECTRIC fields; GRAPHENE; CONDUCTION bands; MAGNETIC fields; MONOMOLECULAR films; FERROELECTRIC thin films
- Publication
Communications Physics, 2024, Vol 7, Issue 1, p1
- ISSN
2399-3650
- Publication type
Article
- DOI
10.1038/s42005-024-01722-6