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We have used ab initio density functional theory, incorporating van der Waals corrections, to study twisted bilayer graphene (TBLG) where Stone-Wales defects or monovacancies are introduced in one of the layers. We compare these results to…

Materials Science · Physics 2015-04-30 Kanchan Ulman , Shobhana Narasimhan

We formulate a low energy effective Hamiltonian to study superlattices in bilayer graphene (BLG) using a minimal model which supports quadratic band touching points. We show that a one dimensional (1D) periodic modulation of the chemical…

Mesoscale and Nanoscale Physics · Physics 2011-08-23 Matthew Killi , Si Wu , Arun Paramekanti

Twisted bilayer graphene (tBLG) has emerged as a promising platform to explore exotic electronic phases. However, the formation of moir\'e patterns in tBLG has thus far been confined to the introduction of twist angles between the layers.…

Materials Science · Physics 2023-10-10 Gabriel R. Schleder , Michele Pizzochero , Efthimios Kaxiras

We demonstrate the generic existence of Dirac cones in the full Bistritzer--MacDonald Hamiltonian for twisted bilayer graphene. Its complementary set, when Dirac cones are absent, is the set of magic angles. We show the stability of magic…

Mathematical Physics · Physics 2024-07-10 Simon Becker , Solomon Quinn , Zhongkai Tao , Alexander Watson , Mengxuan Yang

We study the effect of an in-plane magnetic field on the non-interacting dispersion of twisted bilayer graphene. Our analysis is rooted in the chirally symmetric continuum model, whose zero-field band structure hosts exactly flat bands and…

Strongly Correlated Electrons · Physics 2020-05-20 Yves H. Kwan , S. A. Parameswaran , S. L. Sondhi

Twisted bilayer graphene has been argued theoretically to host exceptionally flat bands when the angle between the two layers falls within a magic range near 1.1$^\circ$. This is now strongly supported by experiment, which furthermore…

Strongly Correlated Electrons · Physics 2019-07-24 Kasra Hejazi , Chunxiao Liu , Leon Balents

Experimental demonstrations of tunable correlation effects in magic-angle twisted bilayer graphene have put two-dimensional moir\'e quantum materials at the forefront of condensed-matter research. Other twisted few-layer graphitic…

Strongly Correlated Electrons · Physics 2021-08-27 Michael M. Scherer , Dante M. Kennes , Laura Classen

We consider magnetic breakdown in twisted bilayer graphene where electrons may hop between semiclassical $k$-space trajectories in different layers. These trajectories within a doubled Brillouin zone constitute a network in which an…

Mesoscale and Nanoscale Physics · Physics 2014-02-11 Chi-Ken Lu , H. A. Fertig

The chiral Hamiltonian for twisted graphene bilayers is written as a $2\times2$ matrix operator by a renormalization of the Hamiltonian that takes into account the particle-hole symmetry. This results in an effective Hamiltonian with an…

Mesoscale and Nanoscale Physics · Physics 2023-08-01 Gerardo G. Naumis , Leonardo A. Navarro-Labastida , Enrique Aguilar-Méndez , Abdiel Espinosa-Champo

Twisted bilayer graphene (TBG) exhibits fascinating correlation-driven phenomena like the superconductivity and Mott insulating state, with flat bands and a chiral lattice structure. We find by quantum transport calculations that the…

Mesoscale and Nanoscale Physics · Physics 2021-02-03 Yizhou Liu , Tobias Holder , Binghai Yan

The nature of charge carriers in twisted bilayer graphene (TBG) near $\nu = -2$, where superconductivity emerges, remains mysterious. While various symmetry-broken ground states have been proposed, experimental evidence of significant…

Strongly Correlated Electrons · Physics 2025-05-14 Patrick J. Ledwith , Ashvin Vishwanath , Eslam Khalaf

Twisted moir\'e superlattices hosting topological flat bands provide a platform to explore the interplay between topology and correlations. Here we investigate topological band structures in $\Gamma$-valley moir\'e systems based on…

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…

Twisted bilayer graphene aligned with hexagonal boron nitride (TBG/hBN) hosts rich topological and correlated quantum phases, such as (fractional) Chern insulators, whose character is dictated by the topology of the moir\'{e} flat band.…

Strongly Correlated Electrons · Physics 2026-05-01 Huiwen Wang , Wei Jiang

Twisted double bilayer graphene (tDBG) has emerged as an especially rich platform for studying strongly correlated and topological states of matter. The material features moir\'e bands that can be continuously deformed by both perpendicular…

Mesoscale and Nanoscale Physics · Physics 2023-12-05 Minhao He , Jiaqi Cai , Ya-Hui Zhang , Yang Liu , Yuhao Li , Takashi Taniguchi , Kenji Watanabe , David H. Cobden , Matthew Yankowitz , Xiaodong Xu

Twisted bilayer graphene near integer fillings hosts correlated single-particle excitations whose dispersion and linewidth are increasingly accessible experimentally. We study these excitations using the topological heavy-fermion model,…

The crystal structure of a material creates a periodic potential that electrons move through giving rise to the electronic band structure of the material. When two-dimensional materials are stacked, the twist angle between the layers…

Strongly Correlated Electrons · Physics 2020-07-07 Zhiming Zhang , Yimeng Wang , Kenji Watanabe , Takashi Taniguchi , Keiji Ueno , Emanuel Tutuc , Brian J. LeRoy

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

The moir\'e superlattice of misaligned atomic bilayers paves the way for designing a new class of materials with wide tunability. In this work, we propose a photonic analog of the moir\'e superlattice based on dielectric resonator…

Mesoscale and Nanoscale Physics · Physics 2023-05-09 Chang-Hwan Yi , Hee Chul Park , Moon Jip Park

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