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In magic angle twisted bilayer graphene, electron-electron interactions play a central role resulting in correlated insulating states at certain integer fillings. Identifying the nature of these insulators is a central question and…

Strongly Correlated Electrons · Physics 2020-08-19 Nick Bultinck , Eslam Khalaf , Shang Liu , Shubhayu Chatterjee , Ashvin Vishwanath , Michael P. Zaletel

We analytically compute the scanning tunneling microscopy (STM) signatures of integer-filled correlated ground states of the magic angle twisted bilayer graphene (TBG) narrow bands. After experimentally validating the strong-coupling…

Magic angle twisted bilayer graphene (MATBG) has become one of the prominent topics in Condensed Matter during the last few years, however, fully atomistic studies of the interacting physics are missing. In this work, we study the…

Mesoscale and Nanoscale Physics · Physics 2023-08-09 Miguel Sánchez Sánchez , Tobias Stauber

We introduce and analyze a model that sheds light on the interplay between correlated insulating states, superconductivity, and flavor-symmetry breaking in magic angle twisted bilayer graphene. Using a variational mean-field theory, we…

Strongly Correlated Electrons · Physics 2021-12-14 Gal Shavit , Erez Berg , Ady Stern , Yuval Oreg

We use self-consistent Hartree-Fock calculations performed in the full $\pi$-band Hilbert space to assess the nature of the recently discovered correlated insulator states in magic-angle twisted bilayer graphene (TBG). We find that gaps…

Strongly Correlated Electrons · Physics 2020-03-11 Ming Xie , Allan H. MacDonald

Correlated insulators are frequently observed in magic angle twisted bilayer graphene at even fillings of electrons or holes per moir\'e unit-cell. Whereas theory predicts these insulators to be intervalley coherent excitonic phases, the…

Mesoscale and Nanoscale Physics · Physics 2023-02-15 Gal Shavit , Kryštof Kolář , Christophe Mora , Felix von Oppen , Yuval Oreg

We investigate correlated insulating states in magic-angle twisted bilayer graphene (TBG) by the exact diagonalization method applied to the extended Hubbard model with interaction parameters recently evaluated in the realistic effective…

Strongly Correlated Electrons · Physics 2018-08-08 Masayuki Ochi , Mikito Koshino , Kazuhiko Kuroki

We derive the exact insulator ground states of the projected Hamiltonian of magic-angle twisted bilayer graphene (TBG) flat bands with Coulomb interactions in various limits, and study the perturbations away from these limits. We define the…

Strongly Correlated Electrons · Physics 2022-04-29 Biao Lian , Zhi-Da Song , Nicolas Regnault , Dmitri K. Efetov , Ali Yazdani , B. Andrei Bernevig

We review analytical and numerical studies of correlated insulating states in twisted bilayer graphene, focusing on real-space lattice models constructions and their unbiased quantum many-body solutions. We show that by constructing…

Strongly Correlated Electrons · Physics 2021-01-12 Yuan Da Liao , Xiao Yan Xu , Zi Yang Meng , Jian Kang

Electron-electron interactions play an important role in graphene and related systems and can induce exotic quantum states, especially in a stacked bilayer with a small twist angle. For bilayer graphene where the two layers are twisted by a…

We present a combined experimental and theoretical study of twisted double bilayer graphene with twist angles between 1{\deg} and 1.35{\deg}. Consistent with moir\'e band structure calculations, we observe insulators at integer moir\'e band…

Mesoscale and Nanoscale Physics · Physics 2019-11-25 G. William Burg , Jihang Zhu , Takashi Taniguchi , Kenji Watanabe , Allan H. MacDonald , Emanuel Tutuc

Motivated by the recently observed insulating states in twisted bilayer graphene, we study the nature of the correlated insulating phases of the twisted bilayer graphene at commensurate filling fractions. We use the continuum model and…

Strongly Correlated Electrons · Physics 2020-07-23 Yi Zhang , Kun Jiang , Ziqiang Wang , Fuchun Zhang

The flat electronic bands in magic-angle twisted bilayer graphene (MATBG) host a variety of correlated insulating ground states, many of which are predicted to support charged excitations with topologically non-trivial spin and/or valley…

The experimentally observed correlated insulating states and quantum anomalous Hall (QAH) effect in twisted bilayer graphene (TBG) have drawn significant attention. However, up to date, the specific mechanisms of these intriguing phenomena…

Strongly Correlated Electrons · Physics 2021-01-27 Jianpeng Liu , Xi Dai

The recently observed superconductivity in twisted bilayer graphene emerges from insulating states believed to arise from electronic correlations. While there have been many proposals to explain the insulating behaviour, the…

Strongly Correlated Electrons · Physics 2020-01-06 J. M. Pizarro , M. J. Calderón , E. Bascones

Motivated by recent experiments indicating strong superconductivity and intricate correlated insulating and flavor-polarized physics in mirror-symmetric twisted trilayer graphene, we study the effects of interactions in this system close to…

Strongly Correlated Electrons · Physics 2022-04-26 Maine Christos , Subir Sachdev , Mathias S. Scheurer

When bilayer graphene is rotationally faulted to an angle $\theta\approx 1.1^\circ$, theory predicts the formation of a flat electronic band and correlated insulating, superconducting, and ferromagnetic states have all been observed at…

Mesoscale and Nanoscale Physics · Physics 2020-09-15 Yu Saito , Jingyuan Ge , Kenji Watanabe , Takashi Taniguchi , Andrea F. Young

Twisted bilayer graphene (TBG) provides a unique framework to elucidate the interplay between strong correlations and topological phenomena in two-dimensional systems. The existence of multiple electronic degrees of freedom -- charge, spin,…

Strongly Correlated Electrons · Physics 2021-01-27 Yuan Da Liao , Jian Kang , Clara N. Breiø , Xiao Yan Xu , Han-Qing Wu , Brian M. Andersen , Rafael M. Fernandes , Zi Yang Meng

Magic-angle twisted bilayer graphene is the best studied physical platform featuring moire potential induced narrow bands with non-trivial topology and strong electronic correlations. Despite their significance, the Chern insulating states…

Mesoscale and Nanoscale Physics · Physics 2024-06-11 Xiaoyu Wang , Oskar Vafek

Two monolayers of graphene twisted by a small `magic' angle exhibit nearly flat bands leading to correlated electronic states and superconductivity, whose precise nature including possible broken symmetries, remain under debate. Here we…

Strongly Correlated Electrons · Physics 2019-12-13 Jong Yeon Lee , Eslam Khalaf , Shang Liu , Xiaomeng Liu , Zeyu Hao , Philip Kim , Ashvin Vishwanath
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