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We have mapped the Dirac point in exfoliated monolayer and bilayer graphene using spatially resolved scanning tunneling spectroscopy (STS) measurements at low temperature. The Dirac point shifts in energy at different locations in graphene.…

Mesoscale and Nanoscale Physics · Physics 2011-02-02 A. Deshpande , W. Bao , Z. Zhao , C. N. Lau , B. J. LeRoy

New developments in the field of topological matter are often driven by materials discovery, including novel topological insulators, Dirac semimetals and Weyl semimetals. In the last few years, large efforts have been performed to classify…

Superlattice in graphene generates extra Dirac points in the band structure and their number depends on the superlattice potential strength. Here, we have created a lateral superlattice in a graphene device with a tunable barrier height…

Ballistically propagating topologically protected states harbor exotic transport phenomena of wide interest. Here we describe a nontopological mechanism that produces such states at the surfaces of generic Dirac materials, giving rise to…

Mesoscale and Nanoscale Physics · Physics 2018-05-25 Oles Shtanko , Leonid Levitov

Three-dimensional topological insulators are characterized by insulating bulk state and metallic surface state involving Dirac fermions that behave as massless relativistic particles. These Dirac fermions are responsible for achieving a…

We investigate the emergence of extra Dirac points in the electronic structure of a periodically spaced barrier system, i.e., a superlattice, on single-layer graphene, using a Dirac-type Hamiltonian. Using square barriers allows us to find…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 M. Barbier , P. Vasilopoulos , F. M. Peeters

We numerically investigate and experimentally demonstrate an in-situ topological band transition in a highly tunable mechanical system made of cylindrical granular particles. This system allows us to tune its inter-particle stiffness in a…

Pattern Formation and Solitons · Physics 2017-07-19 Rajesh Chaunsali , Aman Thakkar , Eunho Kim , Panayotis G. Kevrekidis , Jinkyu Yang

The dynamics of Dirac-Weyl spin-polarized wavepackets driven by periodic electric field is considered for the electrons in a mesoscopic quantum dot formed at the edge of two-dimensional HgTe/CdTe topological insulator with Dirac-Weyl…

Mesoscale and Nanoscale Physics · Physics 2017-01-12 D. V. Khomitsky , A. A. Chubanov , A. A. Konakov

In this paper we present a unifying geometric and compositional framework for modeling complex physical network dynamics as port-Hamiltonian systems on open graphs. Basic idea is to associate with the incidence matrix of the graph a Dirac…

Optimization and Control · Mathematics 2012-09-07 A. J. van der Schaft , B. M. Maschke

Dirac materials, starting with graphene, have drawn tremendous research interest in the past decade. Instead of focusing on the $p_z$ orbital as in graphene, we move a step further and study orbital-active Dirac materials, where the orbital…

Strongly Correlated Electrons · Physics 2023-01-16 Shenglong Xu , Congjun Wu

Graphene, a two dimensional (2D) carbon sheet, acquires many of its amazing properties from the Dirac point nature of its electronic structures with negligible spin-orbit coupling. Extending to 3D space, graphene networks with negative…

Mesoscale and Nanoscale Physics · Physics 2015-07-09 Hongming Weng , Yunye Liang , Qiunan Xu , Rui Yu , Zhong Fang , Xi Dai , Yoshiyuki Kawazoe

Dirac-electronic tunneling and nonlinear transport properties with both finite and zero energy bandgap are investigated for graphene with a tilted potential barrier under a bias. For validation, results from a finite-difference based…

Mesoscale and Nanoscale Physics · Physics 2020-04-01 Farhana Anwar , Andrii Iurov , Danhong Huang , Godfrey Gumbs , Ashwani Sharma

The study of waveguide propagating modes is essential for achieving directional electronic transport in two-dimensional materials. Simultaneously, exploring potential gaps in these systems is crucial for developing devices akin to those…

Mesoscale and Nanoscale Physics · Physics 2023-07-03 V. G. Ibarra-Sierra , E. J. Robles-Raygoza , J. C. Sandoval-Santana , R. Carrillo-Bastos

Wave packets in graphene whose central wave vector is at Dirac points are investigated by numerical calculations. Starting from an initial Gaussian function, these wave packets form into annular peaks that propagate to all directions like…

Quantum Physics · Physics 2012-01-04 Ji Luo , Junqiang Lu , Daniel Valencia

We use the Dirac continuum model to study the propagation of electronic wave packets in graphene with periodically arranged circular potential steps. The time propagation of the wave packets are calculated using the split-operator method…

Mesoscale and Nanoscale Physics · Physics 2025-06-06 M. M. Suleimanov , M. U. Nosirov , H. T. Yusupov , A. Chaves , G. R. Berdiyorov , Kh. Yu. Rakhimov

By viewing the electron as a wavepacket in the positive energy spectrum of the Dirac equation, we are able to achieve a much clearer understanding of its behavior under weak electromagnetic fields. The intrinsic spin magnetic moment is…

General Physics · Physics 2007-09-11 Chih-Piao Chuu , Ming-Che Chang , Qian Niu

The response of electrons under linearly polarized light in Dirac materials as borophene or graphene is analyzed in a continuous wave regime for an arbitrary intense field. Using a rotation and a time-dependent phase transformation, the…

Mesoscale and Nanoscale Physics · Physics 2021-12-03 V. G. Ibarra-Sierra , J. C. Sandoval-Santana , A. Kunold , Saúl A. Herrera , Gerardo G. Naumis

The Dirac cone underlies many unique electronic properties of graphene and topological insulators, and its band structure--two conical bands touching at a single point--has also been realized for photons in waveguide arrays, atoms in…

Dirac points lie at the heart of many fascinating phenomena in condensed matter physics, from massless electrons in graphene to the emergence of conducting edge states in topological insulators [1, 2]. At a Dirac point, two energy bands…

Quantum Gases · Physics 2013-06-26 Leticia Tarruell , Daniel Greif , Thomas Uehlinger , Gregor Jotzu , Tilman Esslinger

We consider a periodically $\delta$-kicked Graphene system with the kicking applied in the $\hat{z}$ direction. This is known to open a gap at the Dirac points by breaking inversion symmetry through the introduction of a time-varying…

Mesoscale and Nanoscale Physics · Physics 2017-09-26 Tridev Mishra , Anurag Pallaprolu , Tapomoy Guha Sarkar , Jayendra N. Bandyopadhyay