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The interaction between carbon nanostructures like quantum dots and radiation can generate different effects inside the nanomaterial, with the use of computational methods such effects can be predicted and optimize the material allowing a…

Mesoscale and Nanoscale Physics · Physics 2022-05-10 Alexander Leon , Juan E. Gomez , Freddy R. Perez

We demonstrate theoretically that quantum dots in bilayers of graphene can be realized. A position-dependent doping breaks the equivalence between the upper and lower layer and lifts the degeneracy of the positive and negative momentum…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 J. Milton Pereira , P. Vasilopoulos , F. M. Peeters

We articulate the challenges and opportunities of unconventional devices using the photon like flow of electrons in graphene, such as Graphene Klein Tunnel (GKT) transistors. The underlying physics is the employment of momentum rather than…

Mesoscale and Nanoscale Physics · Physics 2019-03-01 Mirza M. Elahi , K. M. Masum Habib , Ke Wang , Gil-Ho Lee , Philip Kim , Avik W. Ghosh

We theoretically analyze the scattering process of an electron on a graphene quantum dot (GQD) exposed to an external light irradiation. We prove that for suitable choices of the light polarization state, there emerge scattering resonances,…

Mesoscale and Nanoscale Physics · Physics 2023-09-13 Adrian Pena

Disorder at the etched edges of graphene quantum dots (GQD) enables random all-to-all interactions between localized charges in partially-filled Landau levels, providing a potential platform to realize the Sachdev-Ye-Kitaev (SYK) model. We…

Optical selection rules for one-dimensional graphene nanoribbons are analytically studied and clarified based on the tight-binding model. A theoretical explanation, through analyzing the velocity matrix elements and the features of…

Mesoscale and Nanoscale Physics · Physics 2011-11-03 H. C. Chung , M. H. Lee , C. P. Chang , M. F. Lin

Graphene quantum dots (GQDs) represent single layers up to dozens of graphene layers smaller than 30 nm. GQDs are newish molecules that have aroused great interest in research because of their exceptional and manageable optical, electrical,…

Materials Science · Physics 2021-01-20 Setianto Setianto , Liu Kin Men , Camellia Panatarani , I Made Joni

We consider a square lattice configuration of circular gate-defined quantum dots in an unbiased graphene sheet and calculate the electronic, particularly spectral properties of finite albeit actual sample sized systems by means of a…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 A. Pieper , R. L. Heinisch , G. Wellein , H. Fehske

Density functional theory (DFT) and thermal DFT (thDFT) calculations were used to evaluate the energy band structure, bandgap, and the total energy of various graphene quantum dots (GQDs). The DFT calculations were performed using local…

Materials Science · Physics 2021-12-20 Majid Ghandchi , Ghafar Darvish , Mohammad Kazem Moravvej-Farshi

Graphene and other two-dimensional materials display remarkable optical properties, including a simple light transparency of $T \approx 1 - \pi \alpha$ for light in the visible region. Most theoretical rationalizations of this "universal"…

Mesoscale and Nanoscale Physics · Physics 2016-12-07 Daniel J. Merthe , Vitaly V. Kresin

Optical properties of large arrays of isolated quantum dots are discussed in order to interpret the existent photoluminescence data. The presented theory explains the large observed shift between the lowest emission and absorption energies…

Condensed Matter · Physics 2009-10-28 E. V. Tsiper

The optical conductivity of graphene strained uniaxially is studied within the Kubo-Greenwood formalism. Focusing on inter-band absorption, we analyze and quantify the breakdown of universal transparency in the visible region of the…

Mesoscale and Nanoscale Physics · Physics 2011-01-17 Vitor M. Pereira , R. M. Ribeiro , N. M. R. Peres , A. H. Castro Neto

In this paper we systemically study the optical conductivity and density of states of disorded graphene beyond the Dirac cone approximation. The optical conductivity of graphene is computed by using the Kubo formula, within the framework of…

Mesoscale and Nanoscale Physics · Physics 2011-11-08 Shengjun Yuan , Rafael Roldán , Hans De Raedt , Mikhail I. Katsnelson

We study the electronic and magnetic properties of multilayer quantum dots (MQDs) of graphite in the nearest-neighbor approximation of tight-binding model. We calculate the electronic density of states and orbital susceptibility of the…

Mesoscale and Nanoscale Physics · Physics 2015-01-19 Hazem Abdelsalam , Tania Espinosa-Ortega , Igor Lukyanchuk

Minimal conductivity of a single undoped graphene layer is known to be of the order of the conductance quantum, independent of the electron velocity. We show that this universality does not survive electron-electron interaction which…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 E. G. Mishchenko

We study the transport through evanescent waves in graphene quantum dots of different geometries. The transmission is suppressed when the leads are attached to edges of the same majority sublattice. Otherwise, the transmission depends…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 M. I. Katsnelson , F. Guinea

Spin-polarized first-principles calculations have been performed to tune the electronic and optical properties of graphene (G) and boron-nitride (BN) quantum dots (QDs) through molecular charge-transfer using Tetracyanoquinodimethane (TCNQ)…

Materials Science · Physics 2017-09-13 Arkamita Bandyopadhyay , Sharma SRKC Yamijala , Swapan K Pati

Using the tight-binding approximation we calculated the magnetic susceptibility of graphene quantum dots (GQD) of different geometrical shapes and sizes, smaller than the magnetic length, when the magnetic properties are governed by the…

Mesoscale and Nanoscale Physics · Physics 2013-08-01 T. Espinosa-Ortega , I. A. Luk'yanchuk , Y. G. Rubo

Recently, black phosphorus quantum dots were fabricated experimentally. Motivated by these experiments, we theoretically investigate the electronic and optical properties of rectangular phosphorene quantum dots (RPQDs) in the presence of an…

Mesoscale and Nanoscale Physics · Physics 2017-01-25 L. L. Li , D. Moldovan , W. Xu , F. M. Peeters

In this paper, optical properties of Chiral Graphene Nanoribbons both in longitude and transverse polarization have been studied using density functional theory calculation. It has been shown that the selection rule which have been reported…

Mesoscale and Nanoscale Physics · Physics 2012-05-22 M. Berahman , M. Asad , M. H. Sheikhi