TY - JOUR
T1 - Stacking and gate-tunable topological flat bands, gaps, and anisotropic strip patterns in twisted trilayer graphene
AU - Shin, Jiseon
AU - Chittari, Bheema Lingam
AU - Jung, Jeil
N1 - Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/7/15
Y1 - 2021/7/15
N2 - Trilayer graphene with a twisted middle layer has recently emerged as a new platform exhibiting correlated phases and superconductivity near its magic angle. A detailed characterization of its electronic structure in the parameter space of twist angle θ, interlayer potential difference Δ, and top-bottom layer stacking τ reveals that flat bands with large Coulomb energy versus bandwidth U/W>1 are expected within a range of ±0.2∘ near θ≃1.5∘ and θ≃1.2∘ for τAA top-bottom layer stacking, between a wider 1∘-1.7∘ range for τAB stacking, whose bands often have finite valley Chern numbers thanks to the opening of primary and secondary band gaps in the presence of a finite Δ, and below θ≲0.6∘ for all τ considered. The largest U/W ratios are expected at the magic angle ∼1.5∘ when |Δ|∼0 meV for AA, and slightly below near ∼1.4∘ for finite |Δ|∼25 meV for AB stackings, and near θ∼0.4∘ for both stackings. When τ is the saddle point stacking vector between AB and BA we observe pronounced anisotropic local density of states (LDOS) strip patterns with broken triangular rotational symmetry. We present optical conductivity calculations that reflect the changes in the electronic structure introduced by the stacking and gate tunable system parameters.
AB - Trilayer graphene with a twisted middle layer has recently emerged as a new platform exhibiting correlated phases and superconductivity near its magic angle. A detailed characterization of its electronic structure in the parameter space of twist angle θ, interlayer potential difference Δ, and top-bottom layer stacking τ reveals that flat bands with large Coulomb energy versus bandwidth U/W>1 are expected within a range of ±0.2∘ near θ≃1.5∘ and θ≃1.2∘ for τAA top-bottom layer stacking, between a wider 1∘-1.7∘ range for τAB stacking, whose bands often have finite valley Chern numbers thanks to the opening of primary and secondary band gaps in the presence of a finite Δ, and below θ≲0.6∘ for all τ considered. The largest U/W ratios are expected at the magic angle ∼1.5∘ when |Δ|∼0 meV for AA, and slightly below near ∼1.4∘ for finite |Δ|∼25 meV for AB stackings, and near θ∼0.4∘ for both stackings. When τ is the saddle point stacking vector between AB and BA we observe pronounced anisotropic local density of states (LDOS) strip patterns with broken triangular rotational symmetry. We present optical conductivity calculations that reflect the changes in the electronic structure introduced by the stacking and gate tunable system parameters.
UR - http://www.scopus.com/inward/record.url?scp=85109885059&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.104.045413
DO - 10.1103/PhysRevB.104.045413
M3 - Article
AN - SCOPUS:85109885059
SN - 2469-9950
VL - 104
JO - Physical Review B
JF - Physical Review B
IS - 4
M1 - 045413
ER -