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We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an…

Mesoscale and Nanoscale Physics · Physics 2014-05-05 A. J. Chaves , T. Frederico , O. Oliveira , W. de Paula , M. C. Santos

We consider the optical and transport properties in a model two-dimensional Hamiltonian which describes the merging of two Dirac points. At low energy, in the presence of an energy gap parameter $\Delta$, there are two distinct Dirac points…

Mesoscale and Nanoscale Physics · Physics 2019-08-09 J. P. Carbotte , E. J. Nicol

We study the photoresponse of two-dimensional semi-Dirac semimetals and three-dimensional Dirac semimetals to off-resonant circularly polarized light. For two-dimensional semi-Dirac semimetals we find that incident light does not open a gap…

Mesoscale and Nanoscale Physics · Physics 2015-06-02 Awadhesh Narayan

The interband optical absorption of linearly polarised light by two-dimensional (2D) semimetals hosting tilted and anisotropic Dirac cones in the bandstructure is analysed theoretically. Super-critically tilted (type-II) Dirac cones are…

Mesoscale and Nanoscale Physics · Physics 2022-06-09 A. Wild , E. Mariani , M. E. Portnoi

The possibility of multi-band conductivity and multi-gap superconductivity is explored in oriented V3Si thin films by means of reflectance and transmittance measurements at terahertz frequencies. The temperature dependence of the…

Two-dimensional semimetals with tilted Dirac cones in the electronic band structure are shown to exhibit spatial separation of carriers belonging to different valleys under illumination. In stark contrast to gapped Dirac materials this…

Mesoscale and Nanoscale Physics · Physics 2023-11-08 A. Wild , E. Mariani , M. E. Portnoi

We report a unified theory based on linear response, for analyzing the longitudinal optical conductivity (LOC) of materials with tilted Dirac cones. Depending on the tilt parameter $t$, the Dirac electrons have four phases: untilted,…

Mesoscale and Nanoscale Physics · Physics 2023-11-27 Jian-Tong Hou , Chang-Xu Yan , Chao-Yang Tan , Zhi-Qiang Li , Peng Wang , Hong Guo , Hao-Ran Chang

We have calculated the dynamical optical conductivity for $\alpha-\mathcal{T}_3$ materials in the presence of a finite bandgap in their energy bandstructure. This is a special type of energy dispersions because for all…

Materials Science · Physics 2023-05-31 Andrii Iurov , Liubov Zhemchuzhna , Godfrey Gumbs , Danhong Huang

Dirac electrons, which have been found in the single-component molecular conductor [Pd(dddt)_2] under pressure, are examined by calculating the conductivity and resistivity in terms of a tight-binding model for several pressures of P GPa,…

Strongly Correlated Electrons · Physics 2018-07-10 Yoshikazu Suzumura , HenBo Cui , Reizo Kato

The frequency- and temperature-dependent optical conductivity of the copper oxide materials in the underdoped and optimal doped regimes are studied within the t-J model. The conductivity spectrum shows the unusual behavior at low energies…

Condensed Matter · Physics 2009-10-31 Zhongbing Huang , Shiping Feng

In the framework of Bogoliubov-de Gennes equation, we theoretically study the Andreev reflection in normal-superconducting junctions based on semi-Dirac materials. Owing to the intrinsic anisotropy of semi-Dirac materials, the configuration…

Mesoscale and Nanoscale Physics · Physics 2021-01-06 Hai Li , Xiang Hu , Gang Ouyang

In this paper, we make a comprehensive study of the properties of a gapped Dirac semimetal model, which was originally proposed in the magnetoinfrared spectroscopy measurement of ZeTe$_5$, and includes both the linear and parabolic…

Mesoscale and Nanoscale Physics · Physics 2021-07-13 Yi-Xiang Wang , Fuxiang Li

We present a theoretical investigation of the electronic band structure and optical properties of a two-dimensional anisotropic semimetal that is described by a tilted semi-Dirac type spectrum with a pair of Weyl nodes. We observe that a…

Mesoscale and Nanoscale Physics · Physics 2025-08-13 Suheel Ahmad Malik , M. A. H. Ahshan , SK Firoz Islam

Motivated by the results of recent transport and optical conductivity studies, we propose a semi-infinite two-dimensional lattice model for interacting massive Dirac electrons in the pressurized organic conductor…

Mesoscale and Nanoscale Physics · Physics 2019-09-04 Daigo Ohki , Yukiko Omori , Akito Kobayashi

We study the density of states and the optical conductivity of a Kondo lattice which is immersed in a massless Dirac Fermi sea, as characterized by a linear dispersion relation. As a result of the hybridization $V$ with the $f$-electron…

Strongly Correlated Electrons · Physics 2015-07-16 Hyunyong Lee , Stefan Kettemann

The optical conductivity of MgB$_2$ has been determined on a dense polycrystalline sample in the spectral range 6 meV - 4.6 eV using a combination of ellipsometric and normal incidence reflectivity measurements. $\sigma_{1}(\omega)$…

We report a room-temperature optical reflectivity study performed on [112]-oriented Cd$_3$As$_2$ single crystals over a broad energy range under external pressure up to 10 GPa. The abrupt drop of the band dispersion parameter…

Materials Science · Physics 2018-05-23 E. Uykur , R. Sankar , D. Schmitz , C. A. Kuntscher

The popularity of graphene--a pseudospin-1/2 two-dimensional Dirac-Weyl material--has prompted the search for related materials and the characterization of their properties. In this work, the magneto-optical conductivity is calculated for…

Mesoscale and Nanoscale Physics · Physics 2014-07-10 John D. Malcolm , Elisabeth J. Nicol

We address the optical conductivity of undoped bilayer graphene in the presence of a finite bias voltage at finite temperature. The effects of gap parameter and stacking type on optical conductivity are discussed in the context of tight…

Strongly Correlated Electrons · Physics 2021-06-23 Bahram Maleki , Hamed Rezania

Multi-Weyl semimetals are new types of Weyl semimetals which have anisotropic non-linear energy dispersion and a topological charge larger than one, thus exhibiting a unique quantum response. Using a unified lattice model, we calculate the…

Mesoscale and Nanoscale Physics · Physics 2017-05-03 Seongjin Ahn , E. J. Mele , Hongki Min