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

Fuente: arXiv
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Hauptverfasser: Ezzi, Mohammed M. Al, Peng, Liangtao, Liu, Zhengyu, Chao, Jonah Huang Zi, Pallewela, Gayani N., Foo, Darryl, Adam, Shaffique
Format: Preprint
Veröffentlicht: 2024
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author Ezzi, Mohammed M. Al
Peng, Liangtao
Liu, Zhengyu
Chao, Jonah Huang Zi
Pallewela, Gayani N.
Foo, Darryl
Adam, Shaffique
author_facet Ezzi, Mohammed M. Al
Peng, Liangtao
Liu, Zhengyu
Chao, Jonah Huang Zi
Pallewela, Gayani N.
Foo, Darryl
Adam, Shaffique
contents 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.
format Preprint
id arxiv_https___arxiv_org_abs_2404_17638
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A self-consistent Hartree theory for lattice-relaxed magic-angle twisted bilayer graphene
Ezzi, Mohammed M. Al
Peng, Liangtao
Liu, Zhengyu
Chao, Jonah Huang Zi
Pallewela, Gayani N.
Foo, Darryl
Adam, Shaffique
Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
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.
title A self-consistent Hartree theory for lattice-relaxed magic-angle twisted bilayer graphene
topic Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2404.17638