Graphene is a quasi-2D material formed by carbon atoms in a hexagonal lattice. Graphene-based materials are of great interest for Nanoscience and Nanotechnology, mainly for Nanoelectronics.

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Superconductivity in graphene with spin orbital coupling, is it proper to let the order parameter on two sub-lattice equal?

I am reading this article: Edge superconducting correlation in the attractive-U Kane-Mele-Hubbard model. Considering just the first part of the article, where a negative-U Hubbard model with the ...
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Lattice geometry and dispersion relation

Is there a general theorem which gives some information about which influence have the lattice geometry (for example sub-lattice structure, square lattice, honeycomb lattice, lattice symmetries, ...) ...
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Commercial large scale production of graphene

I am a third year undergraduate Physics student, and for my solid state physics course I am asked to give a short (10 minute) qualitative presentation on the current standings of graphene production, ...
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Does graphene have a honeycomb lattice?

In my grand ignorance I would state that graphene has a honeycomb lattice. Some tend to agree with me and some others do not. I'm curious to know what members of the SE community think is the right ...
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Significance of Dirac cones in condensed matter physics

In condensed matter physics, Dirac cones can be found in graphene, topological insulators, cuprates, and iron-pnictides. This means that electrons behave as massless particles near the Dirac points. ...
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How to generalize BdG equation in order to match a graphene with a metal superconductor?

I want to generalize BdG equation in order to compute the conductance of a junction of graphene with a metal superconductor. The previous works done until now on this hetrojunction is devotted to use ...
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What is the mechanism for graphene to conduct so well?

If metals have always been the best conductors, what is it about graphene that makes it such a good conductor in the plane? Specifically, in the metals silver is better than copper. I always assumed ...
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Does graphene actually remain strong for macroworld engineering?

I heard that people envision strong structural materials made out of graphene, but I heard it may weaken when being stack in layers. Is graphene viable for macroworld structural engineering or is it ...
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What is the Fermi energy of (undoped) graphene?

All of the sources I have found for this online have been wildly unclear. Many use the phrase "Fermi energy" to refer to the "Fermi level" (which is emphatically not what I'm looking for; I want the ...
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Is a “supercritical charge” in graphene similar to Hawking Radiation?

These papers describe a phenomenon referred to as "atomic collapse" and "supercritical charge" in graphene: Wang et al., Pereira et al. "Atomic collapse" appears when you have a large enough Coulomb ...
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A question about Dirac operator

The Dirac operator at 2 dimension can be written as $$ D=\sum_{k=1,2}\sigma^{k}D_{k}=\left( \begin{array}{cc} 0 & \partial_{x}-i\partial_{y}-i(A_x-iA_y)\\ ...
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Defining a gauge field for an anisotropic material under strain

I have a Hamiltonian for a system which is somewhat analogous to graphene but with additional degrees of freedom. The Hamiltonian is $H=\sum_q \Psi^\dagger \mathcal{H}\Psi$ where ...
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Why do we use the massive dirac fermion model for MoS2?

I can derive the massive Dirac fermion Hamiltonian using a tight binding model of graphene with a staggered sublattice potential, but many (including Xiao et al, PRL 2012) use this model for MoS2 as ...
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How come graphene is considered to have two valleys?

The typical graphene band-structure is a double-cone (in opposite directions to each other) with Dirac point in the middle. I assume the bottom cone is like the valence band, while the top cone is ...
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Deriving Graphene energy dispersion in tight binding model

I'm trying to get into graphene, in detail, I try to derive the elec. energy dispersion. Sadly, I am not that familiar with condensed matter QM by now, so I got some basic questions and I hope to find ...
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126 views

Why doesn't Graphene have a band gap?

Is there any simple justification about graphene having no band gap? How bout its linear E-K? Why bilayer graphene has a quadratic E-K and electric field can open a band gap there? I do not ...
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Why is low resistance beneficial to ion exchange membranes?

http://scitation.aip.org/content/aip/journal/jcp/139/11/10.1063/1.4821161 The article states that the graphene filter has a much lower electrical resistance than existing ion exchange membranes, ...
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Graphene Chern number for Dirac nodes

Why do we add winding number at two Dirac nodes to determine topological phase?
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Symmetry argument about degeneracy of graphene energy band at Dirac point

This question is very related to the thread here. In the answer given by @BebopButUnsteady , the statement is that as long as the inversion and time-reversal symmetry are respected, the Dirac points ...
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Thermal exfoliation of graphite oxide

I have been reading up on the production methods of graphene, and one that I found interesting in particular was the thermal exfoliation of graphite oxide. From what I gather the basic idea is that ...
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how does graphene affect the refractive index of an optical waveguide?

Could someone help me find data on the electro conductivity of graphene and its effect on the refractive index of an optical waveguide
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Construct the Hamiltonian of electrons on a graphene sheet ( in xy plane)

Graphene is a two-dimensional material formed by carbon atoms in a honeycomb lattice. Because of the symmetry of the honeycomb lattice, the electrons in graphene obey a linear dispersion relation ...
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XRD of Graphene Foam

At what 2$\theta$ values Graphene Foam shows the peaks in XRD ? I got two peaks at 2$\theta$ values 14.7 degree and 17.2 degree..
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Textbook on 2D Crystals

I've become interested in $2$D crystals, and in particular graphene. I'm looking for a textbook which covers graphene -- possibly as part of a course on solid state theory -- for undergraduates. For ...
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questions about graphene applications

i have read that if we had a sheet of graphene the thickness of cling wrap it would take a elephant on a pencil to pierce it (so two fucktons of psi?) but if graphene is so strong why is it when we ...
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What are the conditions of wave function continuity when solving for Dirac Spinors as done in “Klein paradox” paper by Novoselov?

In the paper "Chiral tunneling and Klein paradox" paper by Katsnelson, Novoselov, and Geim, they use the wave function for Dirac spinors. What are the conditions for continuity of the wave function ...
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Integrals in tight-binding method

In the tight-binding method, as e.g. described in Ashcroft and Mermin one need to solve a few integrals in order to proceed. For example for the overlap between an orbital situated at two different ...
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Graphene: why are there only two Dirac points?

I'm currently studying the simple tight-binding model of graphene, with nearest-neighbour hopping only. It is clear that the energy bands vanish at two distinct points - where the valence and ...
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Effective mass vs. cyclotron mass of carriers (e.g. in graphene)

Since my original question (below) didn't get any answers (maybe it's to specific?), I'd like to rephrase to make it more general. What is the relation between the effective mass and the cyclotron ...
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Alignment of Fermi Levels between Metal and Insulator

If I stick a metal and insulator together, will the Fermi level of the metal align with the insulator? When people draw a band diagram for a metal-oxide-semiconductor heterostructure, I never see ...
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Simple explanation on how to roll up a graphene sheet into a nanotube?

I have read some articles such as http://sinnott.mse.ufl.edu/Backgrounds/theo01_CNT.html and https://www.rose-hulman.edu/math/seminar/seminarfiles/2006-07/abstract2006-11-01.pdf which talk about how ...
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Comparing Graphene and Ni3 HITP2

A recently announced advance in Metallized Organic Films at MIT: http://pubs.acs.org/doi/abs/10.1021/ja502765n discusses a self-organizing material: Ni3HITP2 = ...
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How are semiconductor thermoelectric materials doped?

I have seen various materials quoted as thermoelectric. The current production champion seems to be Bismuth Telluride with a figure of merit Zt of 2.7 or so (but not good above the melting point of ...
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Interpreting a Hamiltonian in terms of 'hopping' operators

I am having some trouble interpreting a Hamiltonian in terms of "hopping" operators. The Huckel model for nearest neighbour interaction in graphene is given by $$H=-t\sum_\vec{R}|\vec ...