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arXiv · 1904.10452

Landau Level Degeneracy in Twisted Bilayer Graphene: Role of Symmetry Breaking

Ya-Hui Zhang·Hoi Chun Po·T. Senthil
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Abstract

The degeneracy of Landau levels flanking charge neutrality in twisted bilayer graphene is known to change from eight-fold to four-fold when the twist angle is reduced to values near the magic angle of $\approx 1.05^\circ$. This degeneracy lifting has been reproduced in experiments by multiple groups, and is known to occur even in devices which do not harbor the correlated insulators and superconductors. We propose $C_3$ symmetry breaking as an explanation of such robust degeneracy lifting, and support our proposal by numerical results on the Landau level spectrum in near-magic-angle twisted bilayer graphene. Motivated by recent experiments, we further consider the effect of $C_2$ symmetry breaking on the Landau levels.

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Ya-Hui Zhang, Hoi Chun Po, T. Senthil. 2019-04-23. Landau Level Degeneracy in Twisted Bilayer Graphene: Role of Symmetry Breaking. https://doi.org/10.1103/physrevb.100.125104

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