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Here we study the systematic evolution of the topological properties of a Chern insulator in presence of an electronic dispersion that can be tuned smoothly from being Dirac-like till a semi-Dirac one and beyond. The band structure under…

Mesoscale and Nanoscale Physics · Physics 2022-03-31 Sayan Mondal , Priyadarshini Kapri , Bashab Dey , Tarun Kanti Ghosh , Saurabh Basu

Much attention has been focused on ways of rendering graphene semiconducting. We study periodically gated graphene in a tight-binding model and find that, contrary to predictions based on the Dirac equation, it is possible to open a band…

Mesoscale and Nanoscale Physics · Physics 2012-10-10 Jesper Goor Pedersen , Thomas Garm Pedersen

We locate gaps in the spectrum of a Hamiltonian on a periodic cuboidal (and generally hyperrectangular) lattice graph with $\delta$ couplings in the vertices. We formulate sufficient conditions under which the number of gaps is finite. As…

Mathematical Physics · Physics 2020-05-26 Ondřej Turek

Quantum Hall phases have recently emerged as a platform to investigate non-Hermitian topology in condensed-matter systems. This platform is particularly interesting due to its tunability, which allows to modify the properties and topology…

Research on graphene has revealed remarkable phenomena arising in the honeycomb lattice. However, the quantum spin Hall effect predicted at the K point could not be observed in graphene and other honeycomb structures of light elements due…

Mesoscale and Nanoscale Physics · Physics 2015-03-23 W. Beugeling , E. Kalesaki , C. Delerue , Y. -M. Niquet , D. Vanmaekelbergh , C. Morais Smith

We study quantum phase transitions in graphene superlattices in external magnetic fields, where a framework is presented to classify multiflavor Dirac fermion critical points describing hopping tuned topological phase transitions of integer…

Strongly Correlated Electrons · Physics 2020-12-11 Jian Wang , Luiz H. Santos

By means of a microwave tight-binding analogue experiment of a graphene-like lattice, we observe a topological transition between a phase with a point-like band gap characteristic of massless Dirac fermions and a gapped phase. By applying a…

Mesoscale and Nanoscale Physics · Physics 2013-05-30 Matthieu Bellec , Ulrich Kuhl , Gilles Montambaux , Fabrice Mortessagne

The Dirac-like quasiparticles in honeycomb graphene lattice are taken to possess a non-zero effective mass. The charge carriers involve to interact with a femtosecond strong laser pulse. Due to the scattering time of electrons in graphene…

Mesoscale and Nanoscale Physics · Physics 2017-01-31 Z. Ahmadi , H. Goudarzi , A. Jafari

We study theoretically "graphene-like" plasmonic metamaterials constituted by two-dimensional arrays of metallic nanoparticles, including perfect honeycomb structures with and without inversion symmetry, as well as generic bipartite…

Mesoscale and Nanoscale Physics · Physics 2015-02-16 Thomas Jebb Sturges , Claire Woollacott , Guillaume Weick , Eros Mariani

The quantum anomalies at the edges correspond to the topological phases in the system, and the chiral edge states can reflect bulk bands' topological properties. In this paper, we demonstrate a simulation of Floquet system's chiral edge…

Quantum Gases · Physics 2020-08-11 Zhongcheng Yu , Jinyuan Tian , Fansu Wei , Xuzong Chen , Xiaoji Zhou

Gap opening in graphene is usually discussed in terms of a semiconducting-like spectrum, where the appearance of a finite gap at the Dirac point is accompanied by a finite mass for the fermions. In this Letter we propose a gap scenario from…

Mesoscale and Nanoscale Physics · Physics 2008-10-03 L. Benfatto , E. Cappelluti

We investigate, in the framework of macroscopic Dirac model, the spectrum, charge density and conductivity of metallic armchair graphene nanoribbons in presence of different mass terms. We reveal the conditions and symmetries governing the…

Mesoscale and Nanoscale Physics · Physics 2018-04-11 C. G. Beneventano , I. V. Fialkovsky , M. Nieto , E. M. Santangelo

Recently the creation of novel topological states of matter by a periodic driving field has attracted great attention. To motivate further experimental and theoretical studies, we investigate interesting aspects of Floquet bands and…

Quantum Gases · Physics 2015-06-19 Longwen Zhou , Hailong Wang , Derek Y. H. Ho , Jiangbin Gong

Twisted double- and mono-bilayer graphene are graphene-based moir\'e materials hosting strongly correlated fermions in a gate-tunable conduction band with a topologically non-trivial character. Using unbiased exact diagonalization…

Strongly Correlated Electrons · Physics 2023-03-22 Patrick H. Wilhelm , Thomas C. Lang , Mathias S. Scheurer , Andreas M. Läuchli

Systems that can be described with the same mathematical models that account for the properties of electrons in graphene are known as graphene-like systems. These include magnons, photons, polaritons, acoustic waves, and electrons in…

Mesoscale and Nanoscale Physics · Physics 2022-10-17 J. L. Lado , J. Fernández-Rossier

The vacuum of a band system, with respect to particles or holes, can become topologically nontrivial when the exceptional points of the non-hermitian Hamiltonian spread over the whole Brillouin zone. The coalescence of the eigenstates…

Mesoscale and Nanoscale Physics · Physics 2021-04-14 YE Xiong

Motivated by the experimental identification of magnetic compounds consisting of zigzag chains, we analyze the band structure topology of magnons in ferromagnets on a zigzag lattice. We account for the general lattice geometry by including…

Mesoscale and Nanoscale Physics · Physics 2024-11-28 Skandan Subramanian , Tom Berlijn , Lucas Lindsay , Randy S. Fishman , John W. Villanova

Periodic networks composed of capacitors and inductors have been demonstrated to possess topological properties with respect to incident electromagnetic waves. Here, we develop an analogy between the mathematical description of waves…

Mesoscale and Nanoscale Physics · Physics 2019-06-12 Rafael Haenel , Timothy Branch , Marcel Franz

We classify all possible 36 gap-opening instabilities in graphene-like structures in two dimensions, i.e., masses of Dirac Hamiltonian when the spin, valley, and superconducting channels are included. These 36 order parameters break up into…

Strongly Correlated Electrons · Physics 2010-01-11 Shinsei Ryu , Christopher Mudry , Chang-Yu Hou , Claudio Chamon

The discovery that the band structure of electronic insulators may be topologically non-trivial has unveiled distinct phases of electronic matter with novel properties. Recently, mechanical lattices have been found to have similarly rich…

Mesoscale and Nanoscale Physics · Physics 2018-10-10 Noah P. Mitchell , Lisa M. Nash , Daniel Hexner , Ari Turner , William T. M. Irvine