Superconductivity, superfluidity and quantum geometry in twisted multilayer systems

P Törmä, S Peotta, BA Bernevig - Nature Reviews Physics, 2022 - nature.com
Superconductivity has been observed in moiré systems such as twisted bilayer graphene,
which host flat, dispersionless electronic bands. In parallel, theory work has discovered that …

Flat bands, strange metals and the Kondo effect

JG Checkelsky, BA Bernevig, P Coleman, Q Si… - Nature Reviews …, 2024 - nature.com
Flat-band materials such as the kagome metals or moiré superlattices are of intense current
interest. Flat bands can result from the electron motion on numerous (special) lattices and …

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 …

Promotion of superconductivity in magic-angle graphene multilayers

Y Zhang, R Polski, C Lewandowski, A Thomson… - Science, 2022 - science.org
Graphene moiré superlattices show an abundance of correlated insulating, topological, and
superconducting phases. Whereas the origins of strong correlations and nontrivial topology …

Imaging inter-valley coherent order in magic-angle twisted trilayer graphene

H Kim, Y Choi, É Lantagne-Hurtubise, C Lewandowski… - Nature, 2023 - nature.com
Magic-angle twisted trilayer graphene (MATTG) exhibits a range of strongly correlated
electronic phases that spontaneously break its underlying symmetries,. Here we investigate …

Twisted bilayer graphene. IV. Exact insulator ground states and phase diagram

B Lian, ZD Song, N Regnault, DK Efetov, A Yazdani… - Physical Review B, 2021 - APS
We derive the exact insulator ground states of the projected Hamiltonian of magic-angle
twisted bilayer graphene (TBG) flat bands with Coulomb interactions in various limits, and …

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 …

Kekulé spiral order at all nonzero integer fillings in twisted bilayer graphene

YH Kwan, G Wagner, T Soejima, MP Zaletel, SH Simon… - Physical Review X, 2021 - APS
We study magic angle graphene in the presence of both strain and particle-hole symmetry
breaking due to nonlocal interlayer tunneling. We perform a self-consistent Hartree-Fock …

Twisted bilayer graphene. V. Exact analytic many-body excitations in Coulomb Hamiltonians: Charge gap, Goldstone modes, and absence of Cooper pairing

BA Bernevig, B Lian, A Cowsik, F **e, N Regnault… - Physical Review B, 2021 - APS
We find exact analytic expressions for the energies and wave functions of the charged and
neutral excitations above the exact ground states (at rational filling per unit cell) of projected …

Twisted bilayer graphene. III. Interacting Hamiltonian and exact symmetries

BA Bernevig, ZD Song, N Regnault, B Lian - Physical Review B, 2021 - APS
We derive the explicit Hamiltonian of twisted bilayer graphene (TBG) with Coulomb
interaction projected into the flat bands and study the symmetries of the Hamiltonian. First …