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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

Magic-angle ($\theta=1.05^\circ$) twisted bilayer graphene (MATBG) has shown two seemingly contradictory characters: the localization and quantum-dot-like behavior in STM experiments, and delocalization in transport experiments. We…

Strongly Correlated Electrons · Physics 2023-01-12 Zhi-Da Song , B. Andrei Bernevig

We develop a model to describe the mixed valence regime in magic-angle twisted bilayer graphene (MATBG) using the recently developed heavy-fermion framework. By employing the large-$N$ slave-boson approach, we derive the self-consistent…

Superconductivity · Physics 2024-07-16 Yantao Li , Benjamin M. Fregoso , Maxim Dzero

Topological heavy fermion models[1-5] describe the flat bands in magic-angle twisted bilayer graphene (MATBG) as arising from the hybridization between localized flat-band orbitals (f-electrons) and nearly-free conduction bands…

Mesoscale and Nanoscale Physics · Physics 2025-03-25 Zhenyuan Zhang , Shuang Wu , Dumitru Călugăru , Haoyu Hu , Takashi Taniguchi , Kenji Wanatabe , Andrei B. Bernevig , Eva Y. Andrei

We develop a perturbative renormalization group (RG) theory for the topological heavy fermion (THF) model, describing magic-angle twisted bilayer graphene (MATBG) as an emergent Anderson lattice. Our theory focuses on an energy window where…

Strongly Correlated Electrons · Physics 2026-01-21 Yi Huang , Yang-Zhi Chou , Sankar Das Sarma

The rich phenomenology of twisted bilayer graphene (TBG) near the magic angle is believed to arise from electron correlations in topological flat bands. An unbiased approach to this problem is highly desirable, but also particularly…

Strongly Correlated Electrons · Physics 2021-09-28 Johannes S. Hofmann , Eslam Khalaf , Ashvin Vishwanath , Erez Berg , Jong Yeon Lee

Recently, Ref. [1] reformulated magic-angle twisted bilayer graphene (MATBG) as a topological heavy fermion problem, and used this reformulation to provide a deeper understanding for the correlated phases at integer fillings. In this work,…

Mesoscale and Nanoscale Physics · Physics 2023-08-21 Jiabin Yu , Ming Xie , B. Andrei Bernevig , Sankar Das Sarma

We investigate the topological heavy-fermion (THF) model of magic-angle twisted bilayer graphene (MATBG) in the projected limit, where only the flat bands are present in the low-energy spectrum. Such limit has been previously analyzed in…

Strongly Correlated Electrons · Physics 2025-10-20 Haoyu Hu , Zhi-Da Song , B. Andrei Bernevig

It has been recently postulated, that the strongly correlated flat bands of magicangle twisted bilayer graphene (MATBG) can host coexisting heavy and light carriers. While transport and spectroscopic measurements have shown hints of this…

We systematically study emergent Kondo lattice models from magic-angle twisted bilayer graphene using the topological heavy fermion representation. At the commensurate fillings, we demonstrate a series of symmetric strongly correlated…

Strongly Correlated Electrons · Physics 2023-07-13 Yang-Zhi Chou , Sankar Das Sarma

Magic angle twisted bilayer graphene (MATBG) presents a fascinating platform for investigating the effects of electron interactions in topological flat bands. The Bistritzer-MacDonald (BM) model provides a simplified quantitative…

Strongly Correlated Electrons · Physics 2025-03-11 Zhi-Yu Xiao , Shiwei Zhang

Magic-angle twisted bilayer graphene (MATBG) is notable as a highly tunable platform for investigating strongly correlated phenomena such as high-$T_c$ superconductivity and quantum spin liquids, due to easy control of doping level through…

Mesoscale and Nanoscale Physics · Physics 2020-06-04 Xiao Chen , Shuanglong Liu , James N Fry , Hai-Ping Cheng

The unusual properties of superconductivity in magic-angle twisted bilayer graphene (MATBG) have sparked enormous research interest. However, despite the dedication of intensive experimental efforts and the proposal of several possible…

Electron interactions in quantum materials fundamentally shape their energy bands and, with them, the material's most intriguing quantum phases. Magic angle twisted bilayer graphene (MATBG) has emerged as a model system, where flat bands…

Mesoscale and Nanoscale Physics · Physics 2025-06-27 J. Xiao , A. Inbar , J. Birkbeck , N. Gershon , Y. Zamir , T. Taniguchi , K. Watanabe , E. Berg , S. Ilani

We apply a generalized Schrieffer-Wolff transformation to the extended Anderson-like topological heavy fermion (THF) model for the magic-angle $(\theta=1.05^{\circ})$ twisted bilayer graphene (MATBLG) (Phys. Rev. Lett. 129, 047601 (2022)),…

Strongly Correlated Electrons · Physics 2023-07-26 Haoyu Hu , B. Andrei Bernevig , Alexei M. Tsvelik

The unexpected discovery of superconductivity and strong electron correlation in twisted bilayer graphene (TBG), a system containing only sp electrons, is considered as one of the most intriguing developments in two-dimensional materials in…

Mesoscale and Nanoscale Physics · Physics 2025-04-22 Wei-Chen Wang , Feng-Wu Chen , Kuan-Sen Lin , Justin T. Hou , Ho-Chun Lin , Mei-Yin Chou

Magic-angle twisted bilayer graphene has recently become a thriving material platform realizing correlated electron phenomena taking place within its topological flat bands. Several numerical and analytical methods have been applied to…

Strongly Correlated Electrons · Physics 2021-09-17 Bin-Bin Chen , Yuan Da Liao , Ziyu Chen , Oskar Vafek , Jian Kang , Wei Li , Zi Yang Meng

Through extensive self-consistent Hartree-Fock calculations in a tight-binding model of twisted bilayer graphene (TBG), we show that many-body effects lead to a considerable increase of the bandwidth of the flat bands and, concomitantly, to…

Mesoscale and Nanoscale Physics · Physics 2026-04-30 Miguel Sánchez Sánchez , José González , Tobias Stauber

The rich physics of magic angle twisted bilayer graphene (TBG) results from the Coulomb interactions of electrons in flat bands of non-trivial topology. While the bands' dispersion is well characterized, accessing their topology remains an…

Mesoscale and Nanoscale Physics · Physics 2026-03-10 F. Mesple , P. Mallet , G. Trambly de Laissardière , C. Dutreix , G. Lapertot , J-Y. Veuillen , V. T. Renard

Magic-angle twisted bilayer graphene (MATBG) exhibits a range of correlated phenomena that originate from strong electron-electron interactions. These interactions make the Fermi surface highly susceptible to reconstruction when $ \pm 1,…

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