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We have recently identified a protected topological semimetal in graphene which presents a zero-energy edge mode robust to disorder and interactions. Here, we address the characteristics of this semimetal and show that the $\mathbb{Z}$…

Mesoscale and Nanoscale Physics · Physics 2025-12-15 Karyn Le Hur , Sariah Al Saati

We study the graphene lattice with a curvature effect. The action depicting multilayers of graphene is portrayed in curved spacetime and effective Dirac equation scopes the curvature effect. The magnetic field is responsible for the…

Mesoscale and Nanoscale Physics · Physics 2014-09-11 M. J. I. Khan , M. Kamran , S. Babar

Many systems are topologically trivial in the bulk, but still have non-trivial wavefunctions locally in the Brillouin zone. For example, in a small-gap Dirac material the Berry curvature is strongly peaked, but cancels over the full…

Superconductivity · Physics 2025-04-10 Lena Engström , Pascal Simon , Andrej Mesaros

Topological insulators can be characterized alternatively in terms of bulk or edge properties. We prove the equivalence between the two descriptions for two-dimensional solids in the single-particle picture. We give a new formulation of the…

Mathematical Physics · Physics 2015-06-05 G. M. Graf , M. Porta

Topological materials may exhibit Hall-like currents flowing transversely to the applied electric field even in the absence of a magnetic field. In graphene superlattices, which have broken inversion symmetry, topological currents…

In this work we analyze infinite graphene nanoribbons subjected to non-uniform magnetic fields that produce topological domain walls in the quantum Hall regime. We show how the proximity between edge states from neighboring domains modifies…

Mesoscale and Nanoscale Physics · Physics 2025-11-04 Ricardo Y. Díaz-Bonifaz , Carlos Ramírez

We propose a topological characterization of Hamiltonians describing classical waves. Applying it to the magnetostatic surface spin waves that are important in spintronics applications, we settle the speculation over their topological…

Mesoscale and Nanoscale Physics · Physics 2019-06-03 Kei Yamamoto , Guo Chuan Thiang , Philipp Pirro , Kyoung-Whan Kim , Karin Everschor-Sitte , Eiji Saitoh

We construct a Wannier basis for twisted bilayer graphene that is projected only from the Bloch functions of the twisted bilayer flat bands. The $C_3$ and $C_{2} \mathcal{T}$ symmetries act locally on the Wannier functions while the Wannier…

Mesoscale and Nanoscale Physics · Physics 2022-10-25 Jiawei Zang , Jie Wang , Antoine Georges , Jennifer Cano , Andrew J. Millis

We numerically verify and analytically prove a winding number invariant that correctly predicts the number of edge states in one-dimensional, nearest-neighbor (between unit cells), two-band models with any complex couplings and open…

Mesoscale and Nanoscale Physics · Physics 2025-05-28 Janet Zhong , Heming Wang , Alexander N Poddubny , Shanhui Fan

After the discovery of graphene and its many fascinating properties, there has been a growing interest for the study of "artificial graphenes". These are totally different and novel systems which bear exciting similarities with graphene.…

Mesoscale and Nanoscale Physics · Physics 2019-06-20 Gilles Montambaux

In 2+1D, topological electromagnetic phases are defined as atomic-scale media which host photonic monopoles in the bulk band structure and respect bosonic symmetries. Additionally, they support topologically protected spin-1 edge states,…

Strongly Correlated Electrons · Physics 2019-06-05 Todd Van Mechelen , Zubin Jacob

The study of topological states in electronic structures, which allows robust transport properties against impurities and defects, has been recently extended to the realm of elasticity. This work shows that nontrivial topological flexural…

We introduce $\mathbb Z_2$-valued bulk invariants for symmetry-protected topological phases in $2+1$ dimensional driven quantum systems. These invariants adapt the $W_3$-invariant, expressed as a sum over degeneracy points of the…

Mesoscale and Nanoscale Physics · Physics 2018-01-24 Bastian Höckendorf , Andreas Alvermann , Holger Fehske

An algorithm for mapping the true phonon modes of a film, which are defined by a two-dimensional (2D) Brillouin zone, to the modes of the corresponding bulk material, which are defined by a three-dimensional (3D) Brillouin zone, is…

Mesoscale and Nanoscale Physics · Physics 2020-01-08 Hyun-Young Kim , Kevin D. Parish , Alan J. H. McGaughey

We report the emergence of electronic edge states in time-periodically driven strained armchair terminated graphene nanoribbons. This is done by considering a short-pulse spatial-periodic strain field. Then, the tight-binding Hamiltonian of…

Mesoscale and Nanoscale Physics · Physics 2017-10-18 Pedro Roman-Taboada , Gerardo G. Naumis

Here we provide a general methodology to directly measure the topological currents emerging in the optical lattice implementation of the Haldane model. Alongside the edge currents supported by gapless edge states, transverse currents can…

Mesoscale and Nanoscale Physics · Physics 2020-07-29 Alvaro Rubio-García , Chris N. Self , Juan Jose García-Ripoll , Jiannis K. Pachos

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

Semi-metals are characterized by nodal band structures that give rise to exotic electronic properties. The stability of Dirac semi-metals, such as graphene in two spatial dimensions (2D), requires the presence of lattice symmetries, while…

Mesoscale and Nanoscale Physics · Physics 2016-06-15 Robert-Jan Slager , Vladimir Juricic , Ville Lahtinen , Jan Zaanen

Optical properties of heterostructures composed of layered 2D materials, such as transition metal dichalcogenides (TMDs) and graphene, are broadly explored. Of particular interest are light-induced energy transfer mechanisms in these…

Materials Science · Physics 2024-09-17 Amir Kleiner , Daniel Hernangómez-Pérez , Sivan Refaely-Abramson

Moir\'e materials host a wealth of intertwined correlated and topological states of matter, all arising from flat electronic bands with nontrivial quantum geometry. A prominent example is the family of alternating-twist magic-angle graphene…