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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Graphene is organic or inorganic material?

I have confusion about graphene, whether the material is organic or inorganic. I read that materials with carbon backbone and hydrogens attached (basically hydrocarbons), or materials of living ...
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How can one confirm creation of magnetic graphene?

Recently my high school physics teacher contacted me looking for an expert to ask about this situation. I am paraphrasing his correspondence below: I just had a a student accidentally create ...
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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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Why are Brillouin zones for graphene and monolayers of transition metal dichalcogenides the same?

The geometrical model of graphene is the flat honeycomb lattice, so the Brillouin zone is also flat honeycomb lattice. However, monolayer of transition metal dichalcogenides is not flat as it consists ...
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Topological invariant in 1D

In 2D, with state $\psi(k_x, k_y)$, it is common to calculate measure of topology of material: 1 - Calculate Berry connection $a = -i <\psi | \partial_{\boldsymbol{k}} | \psi>$. 2 - Calculate ...
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2D materials with isotropic Dirac cones

The celebrated material graphene has electrons which can be described by the simple 2D Hamiltonian $H = v_F \left( \sigma_x p_x + \sigma_y p_y \right)$, where $v_F$ is a Fermi velocity. Silicene, ...
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How to plot graphene conductivity as a function of chemical potential and frequency

I want to plot Graphene Complex Conductivity as a function of two variables in Matlab.The variables are chemical potential and freqency, but I am not sure my code would be corect
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29 views

What does a bucked honeycomb lattice mean?

I was going through some literature where they have mention about bucked honeycomb lattice, but I was unable to understand about the bucked honeycomb term.
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Matrix representation of a fermionic creation and annihilation operator in graphene nanoribbons?

From the other question Matrix representation for fermionic annihilation operator, what if we have to find the matrix representation for the operators $a_{\sigma}^{\dagger}(k,n)$ and $b_{\sigma}(k,n)$ ...
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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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238 views

Why does graphene exist?

I started to read some articles on graphene and almost all say that graphene was discovered late because physicists thought it would be unstable. Despite this, I didn't found a clear explanation of ...
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How to measure the Fermi velocity in Dirac materials?

Suppose that one has a Dirac material (e.g., graphene), i.e., a system where there exists a number $N$ of identical Dirac cones (linear dispersion) at the Fermi energy $E_F=0$. How can one measure ...
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How to cut graphene?

How is graphene cut, given that it is similar in strength and hardness to diamond? I assume you cannot just take a pair of regular scissors to a sheet of it and cut out the shape you want?
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What exactly makes transmittance of graphene change from linear to exponential?

Up to 5 layers, the transmittance of graphene is linear (2.3% per layer): (source) Beyond 5 layers (I assume) the transmittance is exponential, following Beer–Lambert law. What gives rise to this ...
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cicumfernatial vector

Once a sheet of graphite is rolled up into a nanotube, the allowed values of k are constrained by the imposition of periodic boundary conditions along the circumferential direction. this periodic ...
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what is the theoretical reason behind the new paper, Highly tunable hybrid metamaterials employing split-ring resonators built using graphene?

A few days ago, a group of University of Exeter physicists published a paper titled: Highly tunable hybrid metamaterials employing split-ring resonators strongly coupled to graphene surface ...
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156 views

Are there measurable quantities which directly depends on the Fermi velocity?

The dispersion relation of electrons in, for example, graphene exhibits Dirac cones. The dispersion relation of a Dirac point at $\mathbf{k}=\mathbf{K}$ is linear in the momentum magnitude: $$E=\pm ...
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Density of states and elliptic integral

It is known, for example Equation (14) in the graphene review of Castro Neto (arXiv), that the full expression for the density of states (DOS) of graphene is in terms of an elliptic integral. Close ...
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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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Josephson junction exceeding the coherence length of the cooper pair

In this recent paper http://arxiv.org/abs/1504.03286, the authors present the data that they measured Fraunhofer-like diffraction pattern in a Josephson junction with graphene sandwiched between ...
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What does a sheet of graphene look like?

What does a sheet of graphene look like? At one atom thick, is it visible to the naked eye? Can it be handled (by hand) with being torn? Can it be felt at all? [Assuming a large enough sheet ...
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338 views

Symmetry arguments for valley physics in graphene with broken inversion

I am trying to understand this paper: http://link.aps.org/doi/10.1103/PhysRevLett.99.236809 (Here is an arXiv version: http://arxiv.org/abs/0709.1274) In the introduction, they mention certain ...
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Could you help me understand this paper (PRL 106:136806)?

I'm struggling to understand the paper PRL 106:136806 (2011). It is highly cited, but I cannot reproduce their results. Let me quickly summarize the authors' argument and raise my questions. It is ...
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Measurements for thermal diffusivity of graphene?

We have known for a long time that graphene has in-plane thermal conductivity ranging between 2000 and 4000 $W m^{-1} K^{-1}$. But in order to model heat transport on a sheet of graphene, we need more ...
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Is there any conductive graphene with functional groups in markets or I have to modify graphene myself?

My thesis is a comparative study between 2 kind of nanocomposites based on graphene. We should use of graphene with and without functional groups and both should be electrical conductive. But I don't ...
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Why is graphene “gate tunable”?

I am reading Geim and Novoselov's classic paper on electrostatic doping of graphene: http://arxiv.org/abs/cond-mat/0410550 Three parts to the same broad question: 1) I am looking for some rigorous ...
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Classical - quantum analogy of Berry phase

I am reading this webpage about Berry phase: http://materia.fisica.unimi.it/manini/berryphase.html I am happily convinced about the first "elementary geometry" example they provide. Now I am trying ...
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Tuning the frequency in graphene

As is well known, the frequency of transverse optical phonons in single layer graphene ranges from $10^{11}$ to $10^{12}$ Hertz. How can one "tune" the frequency to a specific value?
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Graphene space elevator possible?

I just read this story on MIT working on industrial scale, km^2 sheet production of graphene. A quick check of Wikipedia on graphene and Wikipedia on space elevator tells me Measurements have ...
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Why does the n=0 Landau level in graphene have half the degeneracy of the other levels?

I've looked through several papers that talk about the anomalous integer quantum Hall effect of graphene (such as http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.95.146801), and they all state ...
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Why electron acts like massless when it's moving through graphene sheet? [duplicate]

It has been observed that when electron moves through graphene sheet,it shows a relativistic motion.why does that occurs?
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Electrons in graphene will behave as in 2D space?

Will electrons in graphene behave as in pure 2D space, that is they interact with eachother by a Coulomb potential ~ $\ln r$ instead of $1/r$? I think many force lines will "leak" out of graphene ...
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80 views

What is continuum limit (low energy limit) in condense matter physics?

In condensed matter theory, I can sometimes encounter such a term as continuum limit, also known as low energy limit. I have a question about this term, let me illustrate my question through an ...
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why do edge states in Graphene exist between the Valence and Conduction band?

I read in a review that there are 2 Dirac points in graphene, where the conduction band and valence band touch each other. Near these points electrons obey a linear dispersion relation. Breaking of ...
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What color does graphene glow when heated?

If you heat graphene hot enough, what color would it glow? Is the color within the visible range?
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How to calculate the dispersion relation of graphene?

Graphene is a well investigated two-dimensional material in nano-physics. My teacher asked me to calculate its phonon dispersion with interactions between the first and second nearest neighbors, both ...
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Is a “cathode ray drive” feasible?

When I saw the headline, Fuel Free Spacecrafts Using Graphene, I thought it was another reactionless drive, but it turned out to be a bit more plausible :) Original paper here. Long story short, ...
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Klein paradox in graphene

When considering the Klein paradox in graphene Katsnelson, Novoselov and Geim introduce a potential barrier (see http://www.nature.com/nphys/journal/v2/n9/full/nphys384.html). But I cannot understand ...
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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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Importance of thickness of SiO2-substrate for observing graphene's monolayer

I've discovered that one should use 300-nm-thick SiO2 substrate in order to effectively observe graphene's monolayer through optical microscope. If thickness differs even by 5%, i.e. 315 nm, then ...
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How to show time reversal symmetry does not break in the tight binding Hamiltonian for the honeycomb lattice?

The Hamiltonian of the honeycomb lattice is $$ H=\sum_{k\sigma}t(k) a_{k\sigma}^\dagger b_{k\sigma}+h.c $$ Where $t(-k)=t^*(k)$. If we do a time reversal transformation(according the answer to this ...
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Graphene - Can it produce a magnetic field?

So it's probably a quick no on this one, but since I haven't majored in physics or chemistry I have no idea if it's possible to make Graphene generate a magnetic field. Assuming power or current is ...
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Why graphene's substrate is important

I just have some feelings that somehow it is important what specific subtrate is used to grow graphene monolayer on. Some substrates are better, another ones are not so good. But I cannot completely ...
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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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Why is graphene stronger than graphite?

Why is graphene stronger than graphite when graphene is just a single layer while graphite is multiple layers of graphene? And can't we say that diamond and coal also consist of layers of graphene as ...
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Is graphene on a sticky tape strong enough to compete with my hand stretching it?

As we know we can make graphene using sticky tape so after we make graphene on a sticky tape will that thin sheet of graphene on a sticky tape be strong enough to compete with my hand trying to ...
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Effective Mass and Fermi Velocity of Electrons in Graphene:

In graphene, we have (in the low energy limit) the linear energy-momentum dispersion relation: $E=\hbar v_{\rm{F}}|k|$. This expression arises from a tight-binding model, in fact $E =\frac{3\hbar ...
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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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How to derive electron number equation of Bogoliubov Hamiltonian using thermodynamic relations.

My question arise from this article: Edge superconducting correlation in the attractive-U Kane-Mele-Hubbard model. I will describe my question in detail so that you might not need to look into that ...