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We discuss the effect of long-range interactions within the self-consistent Hartree-Fock (HF) approximation in comparison to short-range atomic Hubbard interactions on the band structure of twisted bilayer graphene (TBG) at charge…

Moir\'e superlattice in twisted bilayer graphene has been proven to be a versatile platform for exploring exotic quantum phases. Extensive investigations have been invoked focusing on the zero-magnetic-field phase diagram at the magic twist…

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

Using scanning probe microscopy and spectroscopy, we explore the spatial symmetry of the electronic wavefunctions of twisted bilayer graphene at the "magic angle" of 1.1 degrees. This small twist angle leads to a long wavelength moir\'e…

Mesoscale and Nanoscale Physics · Physics 2020-08-12 Zhiming Zhang , Rachel Myers , Kenji Watanabe , Takashi Taniguchi , Brian J. LeRoy

In the magic-angle twisted bilayer graphene (MA-TBG), strong electron-electron (e-e) correlations caused by the band-flattening lead to many exotic quantum phases such as superconductivity, correlated insulator, ferromagnetism, and quantum…

Materials Science · Physics 2020-05-29 Ya-Ning Ren , Chen Lu , Yu Zhang , Si-Yu Li , Yi-Wen Liu , Chao Yan , Zi-Han Guo , Cheng-Cheng Liu , Fan Yang , Lin He

Magic-angle twisted bilayer graphene exhibits a panoply of many-body phenomena that are intimately tied to the appearance of narrow and well-isolated electronic bands. The microscopic ingredients that are responsible for the complex…

Strongly Correlated Electrons · Physics 2021-10-04 Cyprian Lewandowski , Stevan Nadj-Perge , Debanjan Chowdhury

At partial fillings of its flat electronic bands, magic-angle twisted bilayer graphene (MATBG) hosts a rich variety of competing correlated phases that show sample to sample variations. Divergent phase diagrams in MATBG are often attributed…

Mesoscale and Nanoscale Physics · Physics 2023-07-12 Dillon Wong , Kevin P. Nuckolls , Myungchul Oh , Ryan L. Lee , Kenji Watanabe , Takashi Taniguchi , Ali Yazdani

Evidence of flat-band magnetism and half-metallicity in compressed twisted bilayer graphene is provided with first-principles calculations. We show that dynamic band-structure engineering in twisted bilayer graphene is possible by…

Materials Science · Physics 2019-06-05 Alejandro Lopez-Bezanilla

At certain angles of rotation called `magic angles' twisted bilayer graphene features almost flat bands. The resulting strong correlations drive the system to novel phases which have been observed in experiments recently. A complete…

Mesoscale and Nanoscale Physics · Physics 2018-11-01 Steven C. Carter , Hridis K. Pal , M. Kindermann

The moir\'e of twisted graphene bilayers can generate flat bands in which charge carriers do not posses enough kinetic energy to escape Coulomb interactions with each other leading to the formation of novel strongly correlated electronic…

Mesoscale and Nanoscale Physics · Physics 2021-09-22 F. Mesple , A. Missaoui , T. Cea , L. Huder , G. Trambly de Laissardière , F. Guinea , C. Chapelier , V. T. Renard

We investigate twisted double bilayer graphene (TDBG), a four-layer system composed of two AB-stacked graphene bilayers rotated with respect to each other by a small angle. Our ab initio band structure calculations reveal a considerable…

Mesoscale and Nanoscale Physics · Physics 2020-04-22 Fatemeh Haddadi , QuanSheng Wu , Alex J. Kruchkov , Oleg V. Yazyev

The discovery of superconducting and insulating states in magic angle twisted bilayer graphene (MATBG) has ignited considerable interest in understanding the nature of electronic interactions in this chemically pristine material system. The…

Mesoscale and Nanoscale Physics · Physics 2019-08-02 Yonglong Xie , Biao Lian , Berthold Jäck , Xiaomeng Liu , Cheng-Li Chiu , Kenji Watanabe , Takashi Taniguchi , B. Andrei Bernevig , Ali Yazdani

In this work, we determine states of electronic order of small-angle twisted bilayer graphene. Ground states are determined for weak and strong couplings which are representatives for varying distances of the twist-angle from its magic…

Strongly Correlated Electrons · Physics 2020-05-29 Markus J. Klug

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

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…

Strongly Correlated Electrons · Physics 2024-04-30 Mohammed M. Al Ezzi , Liangtao Peng , Zhengyu Liu , Jonah Huang Zi Chao , Gayani N. Pallewela , Darryl Foo , Shaffique Adam

A number of moir\'e graphene systems have nearly flat topological bands where electron motion is strongly correlated. Though microscopically these systems are only quasiperiodic, they can typically be treated as translation invariant to an…

Mesoscale and Nanoscale Physics · Physics 2021-03-10 Dan Mao , T. Senthil

In disordered lattices, itinerant electrons typically undergo Anderson localization due to random phase interference, which suppresses their motion. By contrast, in flat-band systems where electrons are intrinsically localized owing to…

Mesoscale and Nanoscale Physics · Physics 2026-04-28 Zhe Hou , Hailong Li , Qing Yan , Yu-Hang Li , Hua Jiang

Twisted Bilayer Graphene at the magic twist angle features flat energy bands, which lead to superconductivity and strong correlation physics. These unique properties are typically limited to a narrow range of twist angles around the magic…

Strongly Correlated Electrons · Physics 2020-10-20 Or Katz , Gil Refael , Netanel H. Lindner

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…

Identifying the microscopic mechanism for superconductivity in magic-angle twisted bilayer graphene (MATBG) is an outstanding open problem. While MATBG exhibits a rich phase-diagram, driven partly by the strong interactions relative to the…

Superconductivity · Physics 2021-06-09 Cyprian Lewandowski , Debanjan Chowdhury , Jonathan Ruhman