TY - JOUR
T1 - Moiré fractional Chern insulators. II. First-principles calculations and continuum models of rhombohedral graphene superlattices
AU - Herzog-Arbeitman, Jonah
AU - Wang, Yuzhi
AU - Liu, Jiaxuan
AU - Tam, Pok Man
AU - Qi, Ziyue
AU - Jia, Yujin
AU - Efetov, Dmitri K.
AU - Vafek, Oskar
AU - Regnault, Nicolas
AU - Weng, Hongming
AU - Wu, Quansheng
AU - Bernevig, B. Andrei
AU - Yu, Jiabin
N1 - Publisher Copyright:
© 2024 American Physical Society.
PY - 2024/5/15
Y1 - 2024/5/15
N2 - The experimental discovery of fractional Chern insulators (FCIs) in rhombohedral pentalayer graphene twisted on hexagonal boron nitride (hBN) has preceded theoretical prediction. Supported by large-scale first-principles relaxation calculations at the experimental twist angle of 0.77°, we obtain an accurate continuum model of n=3,4,5,6,7 layer rhombohedral graphene-hBN moiré systems. Focusing on the pentalayer case, we analytically explain the robust |C|=0,5 Chern numbers seen in the low-energy single-particle bands and their flattening with displacement field, making use of a minimal two-flavor continuum Hamiltonian derived from the full model. We then predict nonzero valley Chern numbers at the ν=-4,0 insulators observed in experiment. Our analysis makes clear the importance of displacement field and the moiré potential in producing localized "heavy fermion"charge density in the top valence band, in addition to the nearly free conduction band. Lastly, we study doubly aligned devices as additional platforms for moiré FCIs with higher Chern number bands.
AB - The experimental discovery of fractional Chern insulators (FCIs) in rhombohedral pentalayer graphene twisted on hexagonal boron nitride (hBN) has preceded theoretical prediction. Supported by large-scale first-principles relaxation calculations at the experimental twist angle of 0.77°, we obtain an accurate continuum model of n=3,4,5,6,7 layer rhombohedral graphene-hBN moiré systems. Focusing on the pentalayer case, we analytically explain the robust |C|=0,5 Chern numbers seen in the low-energy single-particle bands and their flattening with displacement field, making use of a minimal two-flavor continuum Hamiltonian derived from the full model. We then predict nonzero valley Chern numbers at the ν=-4,0 insulators observed in experiment. Our analysis makes clear the importance of displacement field and the moiré potential in producing localized "heavy fermion"charge density in the top valence band, in addition to the nearly free conduction band. Lastly, we study doubly aligned devices as additional platforms for moiré FCIs with higher Chern number bands.
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U2 - 10.1103/PhysRevB.109.205122
DO - 10.1103/PhysRevB.109.205122
M3 - Article
AN - SCOPUS:85192679376
SN - 2469-9950
VL - 109
JO - Physical Review B
JF - Physical Review B
IS - 20
M1 - 205122
ER -