Correlated insulating phases of twisted bilayer graphene at commensurate filling fractions: A Hartree-Fock study

Journal Article · Mon Jul 20 00:00:00 EDT 2020 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.102.035136· OSTI ID:1800971

Zhang, Yi ^[1]; Jiang, Kun ^[2]; Wang, Ziqiang ^[3]; Zhang, Fuchun ^[4]

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1. University of Chinese Academy of Sciences, Beijing (China); OSTI
2. Chinese Academy of Sciences (CAS), Beijing (China); Boston College, Chestnut Hill, MA (United States)
3. Boston College, Chestnut Hill, MA (United States)
4. University of Chinese Academy of Sciences, Beijing (China)

Motivated by the recently observed insulating states in twisted bilayer graphene, we study the nature of the correlated insulating phases of the twisted bilayer graphene at commensurate filling fractions. Iin this work, we use the continuum model and project the Coulomb interaction onto the flat bands to study the ground states by using a Hartree-Fock approximation. In the absence of the hexagonal boron nitride substrate, the ground states are the intervalley coherence states at charge neutrality (filling $$\textit{ν}$$ = 0 , or four electrons per moiré cell) and at $$\textit{ν}$$ = –1/4 and –1/2 (three and two electrons per cell, respectively) and the $$C_2\mathcal{T}$$ symmetry-broken state at $$\textit{ν}$$ = –3/4 (one electron per cell). The hexagonal boron nitride substrate drives the ground states at all $$\textit{ν}$$ into $$C_2\mathcal{T}$$ symmetry broken-states. Our results provide good reference points for further study of the rich correlated physics in the twisted bilayer graphene.

• Research Organization: Boston College, Chestnut Hill, MA (United States)
• Sponsoring Organization: National Natural Science Foundation of China (NSFC); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: FG02-99ER45747
• OSTI ID: 1800971
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 3 Vol. 102; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Materials Science
Physics