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Graphene provides a canonical setting for Floquet band engineering, where circularly polarized light can dynamically open topological gaps at Dirac points and generate nonequilibrium Hall responses. Here we show that uniaxial strain and…

Mesoscale and Nanoscale Physics · Physics 2026-05-27 Yu-Wen Xu , Xiaolin Wan , Zi-Ming Wang , Rui Wang , Dong-Hui Xu

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

In the presence of a circularly polarized mid-infrared radiation graphene develops dynamical band gaps in its quasi-energy band structure and becomes a Floquet insulator. Here we analyze how topologically protected edge states arise inside…

Mesoscale and Nanoscale Physics · Physics 2014-09-23 Gonzalo Usaj , P. M. Perez-Piskunow , L. E. F. Foa Torres , C. A. Balseiro

Nonequilibrium Floquet topological phases due to periodic driving are known to exhibit rich and interesting features with no static analogs. Various known topological invariants usually proposed to characterize static topological systems…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 Muhammad Umer , Raditya Weda Bomantara , Jiangbin Gong

We propose spin valves where a 2D non-magnetic conductor is intercalated between two ferromagnetic insulating layers. In this setup, the relative orientation of the magnetizations of the insulating layers can have a strong impact on the…

Mesoscale and Nanoscale Physics · Physics 2018-08-15 C. Cardoso , D. Soriano , N. A. García-Martínez , J. Fernández-Rossier

We construct a two-channel scattering model for the triangular network of valley Hall states in interlayer-biased minimally twisted bilayer graphene from symmetry arguments and investigate electronic transport in a four-terminal setup. In…

Mesoscale and Nanoscale Physics · Physics 2021-11-10 Christophe De Beule , Fernando Dominguez , Patrik Recher

Using elementary graph theory, we show the existence of interface chiral modes in random oriented scattering networks and discuss their topological nature. For particular regular networks (e.g. L-lattice, Kagome and triangular networks), an…

Mesoscale and Nanoscale Physics · Physics 2020-06-08 Pierre Delplace

Motivated by the recent experimental realization of twisted trilayer graphene and the observed superconductivity that is associated with its flat bands at specific angles, we study trilayer graphene under the influence of different forms of…

Mesoscale and Nanoscale Physics · Physics 2021-12-08 I. A. Assi , J. P. F. LeBlanc , Martin Rodriguez-Vega , Hocine Bahlouli , Michael Vogl

Twisted bilayer graphene (TBG) near "magic angles" has emerged as a rich platform for strongly correlated states of two-dimensional Dirac semimetals. Here we show that twisted bilayers of thin-film magnetic topological insulators (MTI) with…

Mesoscale and Nanoscale Physics · Physics 2022-09-07 Gaurav Chaudhary , Anton A. Burkov , Olle G. Heinonen

Materials with flat electronic bands often exhibit exotic quantum phenomena owing to strong correlations. Remarkably, an isolated low-energy flat band can be induced in bilayer graphene by simply rotating the layers to 1.1$^{\circ}$,…

Mesoscale and Nanoscale Physics · Physics 2019-01-29 Matthew Yankowitz , Shaowen Chen , Hryhoriy Polshyn , K. Watanabe , T. Taniguchi , David Graf , Andrea F. Young , Cory R. Dean

We demonstrate that a single layer of graphene subject to a superlattice potential nearly commensurate to a $\sqrt{3} \times \sqrt{3}$ supercell exactly maps to the chiral model of twisted bilayer graphene, albeit with half as many degrees…

Mesoscale and Nanoscale Physics · Physics 2024-01-18 Valentin Crépel , Aaron Dunbrack , Daniele Guerci , John Bonini , Jennifer Cano

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

Floquet states of periodically driven systems could exhibit rich topological properties. Many of them are absent in their static counterparts. One such example is the chiral edge states in anomalous Floquet topological insulators, whose…

Mesoscale and Nanoscale Physics · Physics 2018-07-03 Longwen Zhou , Jiangbin Gong

We extend the notion of fragile topology to periodically-driven systems. We demonstrate driving-induced fragile topology in two different models, namely, the Floquet honeycomb model and the Floquet $\pi$-flux square-lattice model. In both…

Mesoscale and Nanoscale Physics · Physics 2021-03-31 Rui-Xing Zhang , Zhi-Cheng Yang

Topological semimetals with nodal line are a novel class of topological matter extending the concept of topological matter beyond topological insulators and Weyl/Dirac semimetals. Here, we show that a Floquet topological semimetal with…

Strongly Correlated Electrons · Physics 2019-04-03 Kun Woo Kim , Hyun Woong Kwon , Kwon Park

We propose Floquet chiral topological superconducting systems hosting Floquet Majorana fermions, which consist of hexagonal lattices in proximity to superconductors with shining circularly polarized light. Specially for bilayer graphene…

Mesoscale and Nanoscale Physics · Physics 2015-11-20 Zi-bo Wang , Hua Jiang , Haiwen Liu , X. C. Xie

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 theoretically investigate a folded bilayer graphene structure as an experimentally realizable platform to produce the one-dimensional topological zero-line modes. We demonstrate that the folded bilayer graphene under an external gate…

Mesoscale and Nanoscale Physics · Physics 2018-12-26 Tao Hou , Guanghui Chen , Wang-Kong Tse , Changgan Zeng , Zhenhua Qiao

Minimally twisted bilayer graphene in the presence of an interlayer bias develops a triangular network of valley chiral modes that propagate along the $AB/BA$ interfaces and scatter at the $AA$ regions. The low energy physics of the…

Mesoscale and Nanoscale Physics · Physics 2023-12-07 P. Wittig , F. Dominguez , C. De Beule , P. Recher

Bernal-stacked bilayer graphene modulated by a superlattice potential is a highly tunable system predicted to realize isolated topological flat bands. In this work we calculate the band structure and quantum geometry of bilayer graphene…

Mesoscale and Nanoscale Physics · Physics 2025-05-12 Dathan Ault-McCoy , M. Nabil Y. Lhachemi , Aaron Dunbrack , Sayed Ali Akbar Ghorashi , Jennifer Cano