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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 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

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…

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 electronic properties of bilayer graphene strongly depend on relative orientation of the two atomic lattices. Whereas Bernal-stacked graphene is most commonly studied, a rotational mismatch between layers opens up a whole new field of…

Mesoscale and Nanoscale Physics · Physics 2014-12-15 Hennrik Schmidt , Johannes C. Rode , Dmitri Smirnov , Rolf J. Haug

We demonstrate that single layer graphene exhibits the electronic structure of a bilayer when it is connected to two gated bilayers. The energy gap characteristic for gated bilayer is induced in the single layer and it persists for…

Mesoscale and Nanoscale Physics · Physics 2019-07-31 Wlodzimierz Jaskolski

Due to low dimensionality, the controlled stacking of the graphene films and their electronic properties are susceptible to environmental changes including strain. The strain-induced modification of the electronic properties such as the…

Mesoscale and Nanoscale Physics · Physics 2020-11-10 Zahra Khatibi , Afshin Namiranian , Fariborz Parhizgar

One- and two-dimensional bilayer systems are examples of ultra-tunable quantum materials that are considered as the basis for the new generation of electronic and photonic devices. Here we develop a general theory of the electron band…

Mesoscale and Nanoscale Physics · Physics 2022-06-22 D. V. Chalin , D. I. Levshov , A. E. Myasnikova , S. B. Rochal

The valleys in hexagonal two-dimensional systems with broken inversion symmetry carry an intrinsic orbital magnetic moment. Despite this, such systems possess zero net magnetization unless additional symmetries are broken, since the…

Mesoscale and Nanoscale Physics · Physics 2021-06-30 Brian T. Schaefer , Katja C. Nowack

We theoretically study the electronic structure of small-angle twisted bilayer graphene with a large potential asymmetry between the top and bottom layers. We show that the emergent helical states known to appear on the triangular AB-BA…

Mesoscale and Nanoscale Physics · Physics 2020-03-18 Bonnie Tsim , Nguyen N. T. Nam , Mikito Koshino

Twisted 2D layered materials have garnered a lot of attention recently as a class of 2D materials whose interlayer interactions and electronic properties are dictated by the relative rotation / twist angle between the adjacent layers. In…

In this paper, the electronic properties of 30{\deg} twisted double bilayer graphene, which loses the translational symmetry due to the incommensurate twist angle, are studied by means of the tight-binding approximation. We demonstrate the…

Materials Science · Physics 2020-09-14 Guodong Yu , Zewen Wu , Zhen Zhan , Mikhail I. Katsnelson , Shengjun Yuan

Bilayer graphene twisted by a small angle shows a significant charge modulation away from neutrality, as the charge in the narrow bands near the Dirac point is mostly localized in the regions of the Moir\'e pattern with $AA$ stacking. The…

Mesoscale and Nanoscale Physics · Physics 2018-12-13 Francisco Guinea , Niels R. Walet

Double layer graphene is a gapless semiconductor which develops a finite gap when the layers are placed at different electrostatic potentials. We study, within the tight-biding approximation, the electronic properties of the gaped graphene…

Mesoscale and Nanoscale Physics · Physics 2007-11-26 Eduardo V. Castro , N. M. R. Peres , J. M. B. Lopes dos Santos

So far the physics of moir\'e graphene bilayers at large, incommensurate rotation angles has been considered uninteresting. It has been held that the interlayer coupling in such structures is weak and the system can be thought of as a pair…

Mesoscale and Nanoscale Physics · Physics 2019-11-01 Hridis K. Pal , Stephen Spitz , Markus Kindermann

Twisted bilayer graphene (tBLG) provides a fascinating platform for engineering flat bands and inducing correlated phenomena. By designing the stacking architecture of graphene layers, twisted multilayer graphene can exhibit different…

In this work, we perform ab initio calculations, based on the density functional theory, of the effects on the graphene bilayer when we intercalate carbon atoms between the layers. We use the unit cell of the bilayer to construct larger…

Mesoscale and Nanoscale Physics · Physics 2020-01-31 A. K. M. Pinto , N. F. Frazão , D. L. Azevedo , F. Moraes

By means of atomistic tight-binding calculations, we investigate the effects of uniaxial strain on the electronic bandstructure of twisted graphene bilayer. We find that the bandstructure is dramatically deformed and the degeneracy of the…

Mesoscale and Nanoscale Physics · Physics 2015-07-13 Viet Hung Nguyen , Philippe Dollfus

We present electronic structure calculations of twisted double bilayer graphene (TDBG): A tetralayer graphene structure composed of two AB-stacked graphene bilayers with a relative rotation angle between them. Using first-principles…

Mesoscale and Nanoscale Physics · Physics 2019-11-05 F. J. Culchac , Rodrigo B. Capaz , Leonor Chico , E. Suarez Morell

Intrinsic bilayer graphene is a gapless semimetal. Under the application of a bias field it becomes a semiconductor with a direct band gap that is proportional to the applied field. Under a layer-asymmetric strain (where the upper layer…

Mesoscale and Nanoscale Physics · Physics 2014-12-04 J. A. Crosse