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We develop a two stage renormalization group which connects the continuum Hamiltonian for twisted bilayer graphene at length scales shorter than the moire superlattice period to the Hamiltonian for the active narrow bands only which is…

Strongly Correlated Electrons · Physics 2020-12-21 Oskar Vafek , Jian Kang

Zero energy eigenstates $\psi_0(\theta)$ of the twisted bilayer graphene Hamiltonian at the Dirac point show a high sensitivity to the twist angle $\theta$ near the magic angles where the effective Fermi velocity vanishes. We use…

Mesoscale and Nanoscale Physics · Physics 2025-02-18 Manuel Calixto , Alberto Mayorgas , Octavio Castaños

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

Twisted graphene bilayers develop highly localised states around AA-stacked regions for small twist angles. We show that interaction effects may induce either an antiferromagnetic (AF) and a ferromagnetic (F) polarization of said regions,…

Mesoscale and Nanoscale Physics · Physics 2017-09-13 Luis A. Gonzalez-Arraga , J. L. Lado , Francisco Guinea , Pablo San-Jose

Twisted bilayer graphene (TBG) represents a highly tunable, strongly correlated electron system owed to its unique flat electronic bands. However, understanding the single-particle band structure alone has been challenging due to complex…

We provide a systematic real space derivation of the continuum Hamiltonian for a graphene bilayer starting from a microscopic lattice theory, allowing for an arbitrary inhomogeneous smooth lattice deformation, including a twist. Two…

Strongly Correlated Electrons · Physics 2023-02-24 Oskar Vafek , Jian Kang

We show that the electronic structure of the low-energy bands in the small angle-twisted bilayer graphene consists of a series of semi-metallic and topological phases. In particular we are able to prove, using an approximate low-energy…

Mesoscale and Nanoscale Physics · Physics 2019-07-24 Zhida Song , Zhijun Wang , Wujun Shi , Gang Li , Chen Fang , B. Andrei Bernevig

We show that the flat bands in the chiral model of magic-angle twisted bilayer graphene remain exactly flat in the presence of a perpendicular magnetic field. This is shown by an exact mapping between the model and the lowest Landau level…

Strongly Correlated Electrons · Physics 2021-09-29 Yarden Sheffer , Ady Stern

Twisted bilayer graphene (TBG) exhibits a wide range of intriguing physical properties, such as superconductivity, ferromagnetism, and superlubricity. Depending on the twist angle, periodic moir\'e superlattices form in twisted bilayer…

Mesoscale and Nanoscale Physics · Physics 2022-06-07 Vahid Morovati , Zhiming Xue , Kenneth M. Liechti , Rui Huang

Twisted bilayer graphene exhibits electronic properties that are highly correlated with the size and arrangement of moir\'e patterns. While rigid rotation of two layers creates the topology of moir\'e patterns, local rearrangements of the…

Materials Science · Physics 2023-04-18 Aditya Dey , Shoieb Ahmed Chowdhury , Tara Peña , Sobhit Singh , Stephen M. Wu , Hesam Askari

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

We show that the twisted graphene bilayer can reveal unusual topological properties at low energies, as a consequence of a Dirac-point splitting. These features rely on a symmetry analysis of the electron hopping between the two layers of…

Mesoscale and Nanoscale Physics · Physics 2011-07-21 R. de Gail , M. O. Goerbig , F. Guinea , G. Montambaux , A. H. Castro Neto

The Bistritzer-MacDonald continuum model (BM model) describes the low-energy moir\'e bands for twisted bilayer graphene (TBG) at small twist angles. We derive a generalized continuum model for TBG near any commensurate twist angle, which is…

Mesoscale and Nanoscale Physics · Physics 2022-09-20 Michael G. Scheer , Kaiyuan Gu , Biao Lian

Recent experiments have demonstrated the possibility to design highly controllable junctions on magic angle twisted bilayer graphene, enabling the test of its superconducting transport properties. We show that the presence of chiral pairing…

Mesoscale and Nanoscale Physics · Physics 2023-09-15 Miguel Alvarado , Pablo Burset , Alfredo Levy Yeyati

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

This review article provides a bird's-eye view of what first-principles based methods can contribute to next-generation device design and simulation. After a brief overview of methods and capabilities in the area, we focus on published work…

Mesoscale and Nanoscale Physics · Physics 2020-11-13 Hai-Ping Cheng , Shuanglong Liu , Xiao Chen , Long Zhang , James N Fry

Rotational misalignment or twisting of two mono-layers of graphene strongly influences its electronic properties. Structurally, twisting leads to large periodic supercell structures, which in turn can support intriguing strongly correlated…

We study the localization properties of electrons in incommensurate twisted bilayer graphene for small angles, encompassing the narrow-band regime, by numerically exact means. Sub-ballistic states are found within the narrow-band region…

Mesoscale and Nanoscale Physics · Physics 2022-03-08 Miguel Gonçalves , Hadi Z. Olyaei , Bruno Amorim , Rubem Mondaini , Pedro Ribeiro , Eduardo V. Castro

It has recently been shown that superconductivity in magic-angle twisted trilayer graphene survives to in-plane magnetic fields that are well in excess of the Pauli limit, and much stronger than the in-plane critical magnetic fields of…

Mesoscale and Nanoscale Physics · Physics 2021-09-01 Wei Qin , Allan H. MacDonald

The complete lattice-layer entanglement structure of Bernal stacked bilayer graphene is obtained for the quantum system described by a tight-binding Hamiltonian which includes mass and bias voltage terms. Through a suitable correspondence…

Mesoscale and Nanoscale Physics · Physics 2017-05-23 Victor A. S. V. Bittencourt , Alex. E. Bernardini