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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

We consider the electronic structure of a slightly twisted graphene bilayer and show the coexistence of van Hove singularities (VHSs) and superlattice Dirac points in a continuum approximation. The graphene-on-graphene moir\'e pattern gives…

Mesoscale and Nanoscale Physics · Physics 2013-04-19 Zhao-Dong Chu , Wen-Yu He , Lin He

Recently twisted bilayer graphene (t-BLG) emerges as a new strongly correlated physical platform near a magic twist angle, which hosts many exciting phenomena such as the Mott-like insulating phases, unconventional superconducting behavior…

When layers of graphene are rotationally misaligned by the magic angle, the moir\'e superlattice features extremely flat bands. Due to the enhanced density of states, the Coulomb interaction induces a variety of instabilities. The most…

A series of recent experiments have demonstrated robust superconductivity in magic-angle twisted trilayer graphene (TTG). In particular, a recent work by Cao et al. (arxiv:2103.12083) studies the behavior of the superconductor in an…

Superconductivity · Physics 2021-11-17 Ethan Lake , T. Senthil

We construct a van der Waals heterostructure consisting of three graphene layers stacked with alternating twisting angles $\pm\theta$. At the average twist angle $\theta\sim 1.56^{\circ}$, a theoretically predicted magic angle for the…

Twisted bilayer graphene (tBLG) represents a family of unique materials with optoelectronic properties tuned by the rotation angle between the two layers. The presented work shows an additional way of tweaking the electronic structure of…

When twisted to angles near 1{\deg}, graphene multilayers provide a new window on electron correlation physics by hosting gate-tuneable strongly-correlated states, including insulators, superconductors, and unusual magnets. Here we report…

Small-twist-angle bilayer graphene supports strongly correlated insulating states and superconductivity. Twisted few-layer graphene systems are likely to open up new directions for strong correlation physics in moir\'e superlattices. We…

Materials Science · Physics 2019-07-30 Xiao Li , Fengcheng Wu , Allan H. MacDonald

The emergence of flat bands in twisted bilayer graphene leads to an enhancement of interaction effects, and thus to insulating and superconducting phases at low temperatures, even though the exact mechanism is still widely debated. The…

Strongly Correlated Electrons · Physics 2019-11-15 Tommaso Cea , Niels R. Walet , Francisco Guinea

We investigate the many-body instabilities of electrons interacting near Van Hove singularities arising in monolayer and twisted bilayer graphene. We show that a pairing instability must be dominant over the tendency to magnetic order as…

Mesoscale and Nanoscale Physics · Physics 2015-06-16 J. Gonzalez

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…

Recent experiments have observed possible spin- and valley-polarized insulators and spin-triplet superconductivity in twisted double bilayer graphene, a moire structure consisting of a pair of Bernal-stacked bilayer graphene. Besides the…

Strongly Correlated Electrons · Physics 2020-08-12 Yi-Ting Hsu , Fengcheng Wu , S. Das Sarma

Twisted van der Waals materials provide a tunable platform for investigating two-dimensional superconductivity and quantum phases. Using spectra-imaging scanning tunneling microscopy, we study the superconducting states in twisted bilayer…

Van Hove singularities (VHS's) in the density of states play an outstanding and diverse role for the electronic and thermodynamic properties of crystalline solids. At the critical point the Fermi surface connectivity changes and topological…

Mesoscale and Nanoscale Physics · Physics 2016-12-06 Youngwook Kim , Patrick Herlinger , Pilkyung Moon , Mikito Koshino , Takashi Taniguchi , Kenji Watanabe , Jurgen. H Smet

We study conductance across a twisted bilayer graphene coupled to single-layer graphene leads in two setups: a flake of graphene on top of an infinite graphene ribbon and two overlapping semi-infinite graphene ribbons. We find conductance…

Mesoscale and Nanoscale Physics · Physics 2020-07-30 Hadi Z. Olyaei , Bruno Amorim , Pedro Ribeiro , Eduardo V. Castro

Ultraflat bands have already been detected in twisted bilayer graphene and twisted bilayer transition-metal dichalcogenides, which provide a platform to investigate strong correlations. In this paper, the electronic properties of twisted…

Materials Science · Physics 2024-03-05 Yonggang Li , Zhen Zhan , Shengjun Yuan

Magic-angle twisted trilayer graphene (MATTG) has emerged as a novel moir\'e material that exhibits both strong electronic correlations and unconventional superconductivity. However, spectroscopic studies of its electronic properties are…

We consider the superconducting and Mott-insulating states for the twisted bilayer graphene, modeled as two narrow-band system of electrons with appreciable intraatomic Coulomb interactions. The interaction induces kinetic exchange which…

Superconductivity · Physics 2018-08-29 Maciej Fidrysiak , Michał Zegrodnik , Józef Spałek

Van Hove singularities enhance many-body interactions and induce collective states of matter ranging from superconductivity to magnetism. In magic-angle twisted bilayer graphene, van Hove singularities appear at low energies and are…

Mesoscale and Nanoscale Physics · Physics 2024-08-19 Suvronil Datta , Saisab Bhowmik , Harsh Varshney , Kenji Watanabe , Takashi Taniguchi , Amit Agarwal , U. Chandni