Magic-angle twisted bilayer graphene as a topological heavy fermion problem

ZD Song, BA Bernevig - Physical review letters, 2022 - APS
Magic-angle (θ= 1.0 5°) twisted bilayer graphene (MATBG) has shown two seemingly
contradictory characters: the localization and quantum-dot-like behavior in STM …

Kondo lattice model of magic-angle twisted-bilayer graphene: Hund's rule, local-moment fluctuations, and low-energy effective theory

H Hu, BA Bernevig, AM Tsvelik - Physical review letters, 2023 - APS
We apply a generalized Schrieffer-Wolff transformation to the extended Anderson-like
topological heavy fermion (THF) model for the magic-angle (θ= 1.0 5°) twisted bilayer …

Symmetric kondo lattice states in doped strained twisted bilayer graphene

H Hu, G Rai, L Crippa, J Herzog-Arbeitman… - Physical review …, 2023 - APS
We use the topological heavy fermion (THF) model and its Kondo lattice (KL) formulation to
study the possibility of a symmetric Kondo (SK) state in twisted bilayer graphene. Via a large …

Dynamical correlations and order in magic-angle twisted bilayer graphene

G Rai, L Crippa, D Călugăru, H Hu, F Paoletti… - Physical Review X, 2024 - APS
The interplay of dynamical correlations and electronic ordering is pivotal in sha** phase
diagrams of correlated quantum materials. In magic-angle twisted bilayer graphene …

Magic-angle twisted symmetric trilayer graphene as a topological heavy-fermion problem

J Yu, M **e, BA Bernevig, S Das Sarma - Physical Review B, 2023 - APS
Recently, Song and Bernevig [Phys. Rev. Lett. 129, 047601 (2022) 0031-9007
10.1103/PhysRevLett. 129.047601] reformulated magic-angle twisted bilayer graphene as a …

1/4 is the new 1/2 when topology is intertwined with Mottness

P Mai, J Zhao, BE Feldman, PW Phillips - Nature communications, 2023 - nature.com
In non-interacting systems, bands from non-trivial topology emerge strictly at half-filling and
exhibit either the quantum anomalous Hall or spin Hall effects. Here we show using …

Topological exact flat bands in two-dimensional materials under periodic strain

X Wan, S Sarkar, SZ Lin, K Sun - Physical review letters, 2023 - APS
We study flat bands and their topology in 2D materials with quadratic band crossing points
under periodic strain. In contrast to Dirac points in graphene, where strain acts as a vector …

Phase diagram of twisted bilayer graphene at filling factor

F **e, J Kang, BA Bernevig, O Vafek, N Regnault - Physical Review B, 2023 - APS
We study the correlated insulating phases of twisted bilayer graphene (TBG) in the absence
of lattice strain at integer filling ν=±3. Using the self-consistent Hartree-Fock method on a …

Theory of correlated insulators and superconductivity in twisted bilayer graphene

G Shavit, E Berg, A Stern, Y Oreg - Physical review letters, 2021 - APS
We introduce and analyze a model that sheds light on the interplay between correlated
insulating states, superconductivity, and flavor-symmetry breaking in magic angle twisted …

Moiré phonons in magic-angle twisted bilayer graphene

X Liu, R Peng, Z Sun, J Liu - Nano letters, 2022 - ACS Publications
Magic-angle twisted bilayer graphene (TBG) has attracted significant interest recently due to
the discoveries of diverse correlated and topological states. In this work, we study the …