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Stacking two layers of graphene with a relative twist angle gives rise to moir\'e patterns, which can strongly modify electronic behavior and may lead to unconventional superconductivity. A synthetic version of twisted bilayers can be…

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

Bilayer graphene -- two coupled single graphene layers stacked as in graphite -- provides the only known semiconductor with a gap that can be tuned externally through electric field effect. Here we use a tight binding approach to study how…

Mesoscale and Nanoscale Physics · Physics 2010-04-29 Eduardo V. Castro , N. M. R. Peres , J. M. B. Lopes dos Santos , F. Guinea , A. H. Castro Neto

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

We discuss the effect of elastic deformations on the electronic properties of bilayer graphene membranes. Distortions of the lattice translate into fictitious gauge fields in the electronic Dirac Hamiltonian which are explicitly derived…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Eros Mariani , Alexander J. Pearce , Felix von Oppen

We construct an effective low energy Hamiltonian which describes fermions dwelling on a deformed honeycomb lattice with dislocations and disclinations, and with an arbitrary hopping parameters of the corresponding tight binding model. It…

Mesoscale and Nanoscale Physics · Physics 2021-07-21 Ara Sedrakyan , Andreas Sinner , Klaus Ziegler

Twisted graphene bilayers show a complex electronic structure, further modified by interaction effects. The main features can be obtained from effective models, which make use a few phenomenological parameters. We analyze the influence of…

Strongly Correlated Electrons · Physics 2019-03-04 Niels R. Walet , Francisco Guinea

In mean-field-theory bilayer graphene's massive Dirac fermion model has a family of broken inversion symmetry ground states with charge gaps and flavor dependent spontaneous inter layer charge transfers. We use a lattice Hartree-Fock model…

Mesoscale and Nanoscale Physics · Physics 2011-04-22 Jeil Jung , Fan Zhang , Allan H. MacDonald

We construct an analytic continuum model to describe the electronic structure and the electron-phonon interaction in twisted bilayer graphenes with arbitrary lattice deformation. Starting from the tight-binding model, we derive the…

Mesoscale and Nanoscale Physics · Physics 2020-05-20 Mikito Koshino , Nguyen N. T. Nam

Opening, in a controllable way, the energy gap in the electronic spectrum of graphene is necessary for many potential applications, including an efficient carbon-based transistor. We have shown that this can be achieved by chemical…

Materials Science · Physics 2008-09-05 D. W. Boukhvalov , M. I. Katsnelson

We provide a method for the generation of effective continuum Hamiltonians that goes beyond the well known k.p method in being equally effective in both high, and low (or no) symmetry situations. Our approach is based on a surprising exact…

Mesoscale and Nanoscale Physics · Physics 2019-07-10 N. Ray , F. Rost , D. Weckbecker , M. Vogl , S. Sharma , R. Gupta , O. Pankratov , S. Shallcross

The pairing symmetry of an effective Hamiltonian for interacting fermions on a twisted bilayer graphene superlattice is studied with the determinant quantum Monte Carlo method. The model has the symmetry of a triangle lattice and a…

Strongly Correlated Electrons · Physics 2018-07-03 Huaiming Guo , Xingchuan Zhu , Shiping Feng , Richard T. Scalettar

Parafermions are anyons with the potential for realizing non-local qubits that are resilient to local perturbations. Compared to Majorana zero modes, braiding of parafermions implements an extended set of topologically protected quantum…

Strongly Correlated Electrons · Physics 2024-08-27 Botond Osváth , Gergely Barcza , Örs Legeza , Balázs Dóra , László Oroszlány

Band structure determines the motion of electrons in a solid, giving rise to exotic phenomena when properly engineered. Drawing an analogy between electrons and photons, artificially designed optical lattices indicate the possibility of a…

Mesoscale and Nanoscale Physics · Physics 2019-11-01 Siqi Wang , Xianqing Lin , Mervin Zhao , Changjian Zhang , Sui Yang , Yuan Wang , Kenji Watanabe , Takashi Taniguchi , James Hone , David Tomanek , Xiang Zhang

We show that in bilayer graphene it is possible to achieve a very restrictive confinement of the massless Dirac fermions zero-modes by using inhomogeneous magnetic fields. Specifically, we show that, using a suitable nonuniform magnetic…

Mesoscale and Nanoscale Physics · Physics 2018-11-13 Lucas Sourrouille

We demonstrate that the electronic gap of a graphene bilayer can be controlled externally by applying a gate bias. From the magneto-transport data (Shubnikov-de Haas measurements of the cyclotron mass), and using a tight binding model, we…

We present the electronic band structures of states with the same symmetry as the three-sublattice planar antiferromagnetic order of the triangular lattice. Such states can also be defined on the honeycomb lattice provided the spin density…

Strongly Correlated Electrons · Physics 2018-08-15 Alex Thomson , Shubhayu Chatterjee , Subir Sachdev , Mathias S. Scheurer

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…

The low-energy physics of graphene is described by relativistic Dirac fermions with spin and valley degrees of freedom. Mechanical strain can be used to create a pseudo magnetic field pointing to opposite directions in the two valleys. We…

Strongly Correlated Electrons · Physics 2017-08-29 Ying-Hai Wu , Tao Shi , G. J. Sreejith , Zheng-Xin Liu

We revisit the localized Wannier state description of the twisted bilayer graphene, focusing on the chiral limit. We provide a simple method for constructing such 2D exponentially localized -- yet valley polarized -- Wannier states,…

Strongly Correlated Electrons · Physics 2021-09-02 Oskar Vafek , Jian Kang
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