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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 recent experimental studies of twisted bilayer graphene (TBG) raise a fundamental question: how do we understand Mott localization in a topological band? In this work, we offer a new perspective of Mott physics, which can be generalized…

Strongly Correlated Electrons · Physics 2025-05-20 Jing-Yu Zhao , Boran Zhou , Ya-Hui Zhang

Experiments on graphene bilayers, where the top layer is rotated with respect to the one below, have displayed insulating behavior when the moir\'e bands are partially filled. We calculate the charge distributions in these phases, and…

Strongly Correlated Electrons · Physics 2021-03-15 Ipsita Mandal , Jia Yao , Erich J. Mueller

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

Motivated by the recent observation of correlated insulator states and unconventional superconductivity in twisted bilayer graphene, we study the dependence of electron correlations on the twist angle and reveal the existence of strong…

Strongly Correlated Electrons · Physics 2019-09-18 Zachary A. H. Goodwin , Fabiano Corsetti , Arash A. Mostofi , Johannes Lischner

We report a local minimum in thermal conductivity in twisted bilayer graphene (TBG) at the angle of 1.08$^\circ$, which corresponds to the 'magic angle' in the transition of several other reported properties. Within the supercell of a…

Mesoscale and Nanoscale Physics · Physics 2024-09-12 Yajuan Cheng , Zheyong Fan , Tao Zhang , Masahiro Nomura , Sebastian Volz , Guimei Zhu , Baowen Li , Shiyun Xiong

We present a theory of phonon-mediated superconductivity in near magic angle twisted bilayer graphene. Using a microscopic model for phonon coupling to moir\'e band electrons, we find that phonons generate attractive interactions in both…

Superconductivity · Physics 2018-12-19 Fengcheng Wu , A. H. MacDonald , Ivar Martin

We analyze an analog of the $t$-$J$-$U$ model as applied to the description of a single moir\'e flat band of twisted WSe$_2$ bilayer. To take into account the correlation effects induced by a significant strength of the Coulomb repulsion,…

Strongly Correlated Electrons · Physics 2025-05-15 M. Zegrodnik , A. Biborski

The nature of the correlated phases found in some graphene heterostructures is under debate. We use dynamical mean-field theory (DMFT) to analyze the effect of local correlations close to half-filling on one of such systems, the ABC…

Strongly Correlated Electrons · Physics 2022-08-30 M. J. Calderón , A. Camjayi , E. Bascones

Magic-angle twisted bilayer graphene displays at different fillings of the four flat bands lying around the charge neutrality point a wealth of notable phases that include magnetic Chern insulators, whose magnetization is mostly of orbital…

Strongly Correlated Electrons · Physics 2023-09-07 Andrea Blason , Michele Fabrizio

We show that the insulating states of magic-angle twisted bilayer graphene support a series of collective modes corresponding to local particle-hole excitations on triangular lattice sites. Our theory is based on a continuum model of the…

Strongly Correlated Electrons · Physics 2021-07-09 Ajesh Kumar , Ming Xie , A. H. MacDonald

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

Twisting two layers into a magic angle (MA) of ~1.1{\deg} is found essential to create low energy flat bands and the resulting correlated insulating, superconducting, and magnetic phases in twisted bilayer graphene (TBG). While most of…

Emergent quantum phases driven by electronic interactions can manifest in materials with narrowly dispersing, i.e. "flat", energy bands. Recently, flat bands have been realized in a variety of graphene-based heterostructures using the…

Recently, alternating twist multilayer graphene (ATMG) has emerged as a family of moir\'e systems that share several fundamental properties with twisted bilayer graphene, and are expected to host similarly strong electron-electron…

Mesoscale and Nanoscale Physics · Physics 2022-07-12 G. William Burg , Eslam Khalaf , Yimeng Wang , Kenji Watanabe , Takashi Taniguchi , Emanuel Tutuc

Magic-angle twisted bilayer graphene (MtBLG) has proven to be an extremely promising new platform to realize and study a host of emergent quantum phases arising from the strong correlations in its narrow bandwidth flat band. In this regard,…

We study the effect of Coulomb interaction between two oppositely doped low-dimensional tJ model systems. We exactly show that, in the one-dimensional case, an arbitrarily weak interaction leads to the formation of charge neutral…

Strongly Correlated Electrons · Physics 2009-11-11 Tiago C. Ribeiro , Alexander Seidel , Jung Hoon Han , Dung-Hai Lee

Motivated by the recently experimental reported signatures of the tunable Mott insulating state and superconductivity in an ABC graphene trilayer superlattice, we investigate the charge compressibility, the spin correlation, and the…

Strongly Correlated Electrons · Physics 2021-07-09 Huijia Dai , Junchen Hou , Xiao Zhang , Ying Liang , Tianxing Ma

A number of interesting physical phenomena have been discovered in magic-angle twisted bilayer graphene (MATBG), such as superconductivity, correlated gapped and gapless phases, etc. The gapped phases are believed to be symmetry-breaking…

Strongly Correlated Electrons · Physics 2024-01-19 Geng-Dong Zhou , Yi-Jie Wang , Ninghua Tong , Zhi-Da Song

The flat bands of magic-angle twisted bilayer graphene (MATBG) host strongly-correlated electronic phases such as correlated insulators, superconductors and a strange-metal state. The latter state, believed to be key for understanding the…