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We argue that at finite carrier density and large displacement fields, bilayer graphene is prone to $\ell =0$ and $\ell = 1$ Pomeranchuk Fermi surface instabilities. The broken symmetries are driven by non-local exchange interactions which…

Mesoscale and Nanoscale Physics · Physics 2015-07-08 Jeil Jung , Marco Polini , Allan H. MacDonald

We develop a diagrammatic perturbation theory to account for the emergence of moir\'e bands in the continuum model of twisted bilayer graphene. Our framework is build upon treating the moir\'e potential as a perturbation that transfers…

Mesoscale and Nanoscale Physics · Physics 2024-07-30 Federico Escudero

The effective theory for bilayer graphene (BLG), subject to parallel/in-plane magnetic fields, is derived. With a sizable magnetic field the trigonal warping becomes irrelevant, and one ends up with two Dirac points in the vicinity of each…

Mesoscale and Nanoscale Physics · Physics 2014-01-08 Bitan Roy , Kun Yang

We apply a generalized Schrieffer-Wolff transformation to the extended Anderson-like topological heavy fermion (THF) model for the magic-angle $(\theta=1.05^{\circ})$ twisted bilayer graphene (MATBLG) (Phys. Rev. Lett. 129, 047601 (2022)),…

Strongly Correlated Electrons · Physics 2023-07-26 Haoyu Hu , B. Andrei Bernevig , Alexei M. Tsvelik

We numerically investigate the electronic transport properties between two mesoscopic graphene disks with a twist by employing the density functional theory coupled with non-equilibrium Green's function technique. By attaching two graphene…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 Yulei Han , Yafei Ren , Xinlong Dong , Junjie Zeng , Wei Ren , Zhenhua Qiao

When light is incident on a medium with spatially disordered index of refraction, interference effects lead to near-perfect reflection when the number of dielectric interfaces is large, so that the medium becomes a "transparent mirror." We…

Mesoscale and Nanoscale Physics · Physics 2020-12-29 Sandeep Joy , Saad Khalid , Brian Skinner

The experimental control over the twist angle in twisted bilayer graphene has not been reported and its realistic structure is most likely incommensurate. In this paper, we develop a tight-binding virtual crystal approximation theory to…

Mesoscale and Nanoscale Physics · Physics 2015-01-27 D. Ghader , D. Szczȩśniak , A. Khater

Magic-angle twisted trilayer graphene (MATTG) recently emerged as a highly tunable platform for studying correlated phases of matter, such as correlated insulators and superconductivity. Superconductivity occurs in a range of doping levels…

Identifying the microscopic processes that limit conductivity is essential for understanding correlated and quantum-critical states in quantum materials. In twisted bilayer graphene (TBG) and other twist-controlled materials, the…

The flat electronic bands in magic-angle twisted bilayer graphene (MATBG) host a variety of correlated insulating ground states, many of which are predicted to support charged excitations with topologically non-trivial spin and/or valley…

We present a theoretical investigation of the magnetic properties exhibited by twisted bilayer graphene (TBG) systems with small twist angles, where the appearance of flat minibands strongly enhances electron-electron interaction effects.…

Mesoscale and Nanoscale Physics · Physics 2025-04-08 Kevin J. U. Vidarte , Felipe Pérez Riffo , Eric Suárez Morell , Caio Lewenkopf

We implement a self-consistent Hartree-Fock approximation based on a microscopic model in real space, which allows us to consider the interplay between the Hubbard and the extended Coulomb interaction in twisted bilayer graphene at the…

Mesoscale and Nanoscale Physics · Physics 2021-09-15 J. Gonzalez , T. Stauber

The salient property of the electronic band structure of twisted bilayer graphene (TBG), at the so-called magic angle (MA), is the emergence of flat bands around the charge neutrality point. These bands are associated with the observed…

Mesoscale and Nanoscale Physics · Physics 2023-09-04 Sonia Haddad , Takeo Kato , Jihang Zhu , Lassaad Mandhour

Using exact diagonalization, we study the projected Hamiltonian with Coulomb interaction in the 8 flat bands of first magic angle twisted bilayer graphene. Employing the U(4) (U(4)$\times$U(4)) symmetries in the nonchiral (chiral) flat band…

Strongly Correlated Electrons · Physics 2022-04-26 Fang Xie , Aditya Cowsik , Zhi-Da Song , Biao Lian , B. Andrei Bernevig , Nicolas Regnault

The interplay of twist and strain in bilayer graphene enables the formation of moir\'e patterns and narrow bands that host correlated and topological phases. While magic-angle twisted bilayer graphene has been widely studied, strain…

Mesoscale and Nanoscale Physics · Physics 2026-03-10 Federico Escudero , Dong Wang , Pierre A. Pantaleón , Shengjun Yuan , Francisco Guinea , Zhen Zhan

Twisted bilayer graphene displays many fascinating properties that can be tuned by varying the relative angle (also called twist angle) between its monolayers. As a remarkable feature, both the electronic flat bands and the corresponding…

Materials Science · Physics 2022-05-06 V. Hung Nguyen , Trinh X. Hoang , J. -C. Charlier

Materials with correlated electrons often respond very strongly to external or internal influences, leading to instabilities and states of matter with broken symmetry. This behavior can be studied theoretically either by evaluating the…

Strongly Correlated Electrons · Physics 2017-08-15 J. Kunes , I. Leonov , P. Augustinsky , V. Krapek , M. Kollar , D. Vollhardt

Recent transport studies have demonstrated the great potential of twisted monolayer-bilayer graphene (tMBG) as a new platform to host moir\'e flat bands with a higher tunability than twisted bilayer graphene (tBG). However, a direct…

Mesoscale and Nanoscale Physics · Physics 2024-01-10 Ling-Hui Tong , Qingjun Tong , Li-Zhen Yang , Yue-Ying Zhou , Qilong Wu , Yuan Tian , Li Zhang , Lijie Zhang , Zhihui Qin , Long-Jing Yin

Electronic correlations in two-dimensional materials play a crucial role in stabilising emergent phases of matter. The realisation of correlation-driven phenomena in graphene has remained a longstanding goal, primarily due to the absence of…

Mesoscale and Nanoscale Physics · Physics 2023-09-19 Saisab Bhowmik , Arindam Ghosh , U. Chandni

Exotic electronic physics including correlated insulating states and fractional Chern insulators have been observed in twisted bilayer graphene in a magnetic field when the Fermi velocity vanishes, however a question remains as to the…

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