Unraveling the insulating Chern states of magic-angle twisted bilayer graphene at finite magnetic field via the topological heavy fermion framework

The single particle excitation spectra at integer fillings (s) of the narrow bands of magic-angle twisted bilayer graphene were reported in Ref [1], incorporating the effects of strain and relaxation within the topological heavy fermion (THF) framework. Employing the methods developed in Ref [2], we study the Landau quantization of the ensuing electronic spectra, unveiling a sequence of correlated insulating states with Chern number t for (s, t) = (0, ±4n) and ±(2, 2n) where n is a non-negative integer.  At s = 0, we find the largest gap for the state with t = ±4, the next largest gaps with t = 0, ±8 are comparable, followed by the gap with t = ±12.

References:

[1] J. Herzog-Arbeitman, D. Călugăru, H. Hu, J. Yu, N. Regnault, J. Kang, B. A. Bernevig, and O. Vafek, Kekulé spiral order from strained topological heavy fermions, Phys. Rev. B 112, 125129 (2025).

[2] K. Singh, A. Chew, J. Herzog-Arbeitman, B. A. Bernevig, and O. Vafek, Topological heavy fermions in magnetic field, Nature Communications volume 15, 5257 (2024).