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arXiv · 2102.02256

Exact Diagonalization for Magic-Angle Twisted Bilayer Graphene

Pawel Potasz·Ming Xie·Allan H. MacDonald
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Abstract

We report on finite-size exact-diagonalization calculations in a Hilbert space defined by the continuum-model flat moiré bands of magic angle twisted bilayer graphene (MATBG). For moiré band filling $3>|ν|>2$, where superconductivity is strongest, we obtain evidence that the ground state is a spin ferromagnet. Near $|ν|=3$, we find Chern insulator ground states that have spontaneous spin, valley, and sublattice polarization, and demonstrate that the anisotropy energy in this order-parameter space is strongly band-filling-factor dependent. We emphasize that inclusion of the remote band self-energy is necessary for a reliable description of MATBG flat band correlations.

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Pawel Potasz, Ming Xie, Allan H. MacDonald. 2021-09-30. Exact Diagonalization for Magic-Angle Twisted Bilayer Graphene. https://doi.org/10.1103/physrevlett.127.147203

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