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The electronic bands of twisted bilayer graphene (TBLG) with a large-period moir\'e superlattice fracture to form narrow Bloch minibands that are spectrally isolated by forbidden energy gaps from remote dispersive bands. When these gaps are…

Mesoscale and Nanoscale Physics · Physics 2020-10-28 Vo Tien Phong , E. J. Mele

Magic-angle twisted bilayer graphene (TBG) has attracted significant interest recently due to the discoveries of diverse correlated and topological states in this system. Despite the extensive research on the electron-electron interaction…

Mesoscale and Nanoscale Physics · Physics 2022-10-13 Xiaoqian Liu , Ran Peng , Zhaoru Sun , Jianpeng Liu

Moire superlattices in twisted bilayer graphene (TBG) and its derived structures can host exotic correlated quantum phenomena because the narrow moire flat minibands in those systems effectively enhance the electron-electron interaction.…

Materials Science · Physics 2021-10-18 Qiaoling Xu , Yuzheng Guo , Lede Xian

Our theoretical study unfolds the topological phase transitions (within bands of the Moir\'e super-lattice) in small angle twisted double bilayer graphene (tDBLG) under the influence of external gate voltage and intrinsic spin-orbit…

Mesoscale and Nanoscale Physics · Physics 2025-02-05 Kamalesh Bera , Priyanka Mohan , Arijit Saha

The freestanding twisted bilayer graphene (TBG) is unstable, below a critical twist angle {\theta}_c~3.7 degrees, against a moire (2 \times 1) buckling distortion at T=0. Realistic simulations reveal the concurrent unexpected collapse of…

Mesoscale and Nanoscale Physics · Physics 2023-12-18 Jin Wang , Ali Khosravi , Andrea Silva , Michele Fabrizio , Andrea Vanossi , Erio Tosatti

Twisted bilayer graphene (TBLG) has emerged as an important platform for studying correlated phenomena, including unconventional superconductivity, in two-dimensional systems. The complexity of the atomic-scale structures in TBLG has made…

Strongly Correlated Electrons · Physics 2019-11-07 Stephen Carr , Shiang Fang , Hoi Chun Po , Ashvin Vishwanath , Efthimios Kaxiras

We show that the entire continuous model of twisted bilayer graphene (TBG) (and not just the two active bands) with particle-hole symmetry is anomalous and hence incompatible with a lattice model. Previous works, e.g., [Phys. Rev. Lett.…

Mesoscale and Nanoscale Physics · Physics 2022-04-29 Zhi-Da Song , Biao Lian , Nicolas Regnault , B. Andrei Bernevig

We discuss twisted bilayer graphene (TBG) based on a theorem of flat band ferromagnetism put forward by Mielke and Tasaki. According to this theorem, ferromagnetism occurs if the single particle density matrix of the flat band states is…

Strongly Correlated Electrons · Physics 2020-12-03 R. Pons , A. Mielke , T. Stauber

We study the electronic and topological properties of fully relaxed twisted bilayer (TBG) and double bilayer (TDBG) graphene under perpendicular pressure. An approach has been proposed to obtain the equilibrium in-plane structural…

Mesoscale and Nanoscale Physics · Physics 2020-07-20 Xianqing Lin , Haotian Zhu , Jun Ni

Twisted bilayer graphene (TBG) realizes a highly tunable, strongly interacting system featuring superconductivity and various correlated insulating states. We establish gate-defined wires in TBG with proximity-induced spin-orbit coupling as…

Strongly Correlated Electrons · Physics 2022-02-23 Alex Thomson , Ina Sorensen , Stevan Nadj-Perge , Jason Alicea

At magic twisted angles, Dirac cones in twisted bilayer graphene (TBG) can evolve into flat bands, serving as a critical playground for the study of strongly correlated physics. When chiral symmetry is introduced, rigorous mathematical…

Strongly Correlated Electrons · Physics 2023-10-11 Fan Cui , Congcong Le , Qiang Zhang , Xianxin Wu , Jiangping Hu , Ching-Kai Chiu

The electronic properties of twisted bilayer graphene (TBG) can be dramatically different from those of a single graphene layer, in particular when the two layers are rotated relative to each other by a small angle. TBG has recently…

We show that bilayer graphene in the presence of a 2D superlattice potential provides a highly tunable setup that can realize a variety of flat band phenomena. We focus on two regimes: (i) topological flat bands with non-zero Chern numbers,…

Mesoscale and Nanoscale Physics · Physics 2023-06-16 Sayed Ali Akbar Ghorashi , Aaron Dunbrack , Ahmed Abouelkomsan , Jiacheng Sun , Xu Du , Jennifer Cano

We study the symmetries of twisted trilayer graphene's band structure under various extrinsic perturbations, and analyze the role of long-range electron-electron interactions near the first magic angle. The electronic structure is modified…

Mesoscale and Nanoscale Physics · Physics 2021-10-04 Vo Tien Phong , Pierre A. Pantaleón , Tommaso Cea , Francisco Guinea

Very recently, unconventional superconductivity has been observed in the double twisted trilayer graphene (TLG), where three monolayer graphene (MLG) are stacked on top of each other with two twist angles [J. M. Park, et al., Nature 590,…

Mesoscale and Nanoscale Physics · Physics 2022-06-01 Miao Liang , Meng-Meng Xiao , Zhen Ma , Jin-Hua Gao

We use a lowest Landau level model to study the recent observation of an anomalous Hall effect in twisted bilayer graphene. This effective model is rooted in the occurrence of Chern bands which arise due to the coupling between the graphene…

Strongly Correlated Electrons · Physics 2020-04-28 Nick Bultinck , Shubhayu Chatterjee , Michael P. Zaletel

The recent constructions of flat moir\'e minibands in specifically twisted multilayer graphene and twisted transition metal dichalcogenides (TMDs) have facilitated the observation of strong correlations with a convenient tunability. These…

Mesoscale and Nanoscale Physics · Physics 2024-04-05 Jihang Zhu , Dawei Zhai , Cong Xiao , Wang Yao

Electronic properties of quantum dots (QDs) depend sensitively on their parent materials. Therefore, confined electronic states in graphene QDs (GQDs) of monolayer and Bernal-stacked bilayer graphene are quite different. Twisted bilayer…

Mesoscale and Nanoscale Physics · Physics 2022-01-05 Xiao-Feng Zhou , Yi-Wen Liu , Hong-Yi Yan , Zhong-Qiu Fu , Haiwen Liu , Lin He

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

Twisted bilayer graphene (TBG) can host the moir\'{e} energy flat bands with two-fold degeneracy serving as a fruitful playground for strong correlations and topological phases. However, the number of degeneracy is not limited to two.…

Strongly Correlated Electrons · Physics 2024-06-17 Congcong Le , Qiang Zhang , Cui Fan , Xianxin Wu , Ching-Kai Chiu