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arXiv · 2404.17638

A self-consistent Hartree theory for lattice-relaxed magic-angle twisted bilayer graphene

Mohammed M. Al Ezzi·Liangtao Peng·Zhengyu Liu·Jonah Huang Zi Chao·Gayani N. Pallewela·Darryl Foo·Shaffique Adam
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Abstract

For twisted bilayer graphene close to magic angle, we show that the effects of lattice relaxation and the Hartree interaction both become simultaneously important. Including both effects in a continuum theory reveals a Lifshitz transition to a Fermi surface topology that supports both a ``heavy fermion" pocket and an ultraflat band ($\approx 8~{\rm meV}$) that is pinned to the Fermi energy for a large range of fillings. We provide analytical and numerical results to understand the narrow ``magic angle range" that supports this pinned ultraflat band and make predictions for its experimental observation. We believe that the bands presented here are accurate at high temperature and provide a good starting point to understand the myriad of complex behaviour observed in this system.

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Mohammed M. Al Ezzi, Liangtao Peng, Zhengyu Liu, Jonah Huang Zi Chao, Gayani N. Pallewela, Darryl Foo, Shaffique Adam. 2024-04-26. A self-consistent Hartree theory for lattice-relaxed magic-angle twisted bilayer graphene. https://arxiv.org/abs/2404.17638

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