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.
Questions tagged [graphene]
292 questions
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Mermin-Wagner and graphene
I have been told that the Mermin-Wagner theorem disallows the existence of the crystal of graphene. However, I don't have enough knowledge to understand the Mermin-Wagner theorem. If possible can someone please explain to me:
The basics of the…
PackSciences
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15
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Graphene and Klein bottle?
I am trying to understand graphene as a topological insulator.
The spin orbital interaction in graphene is very small (~10mK?). But if we consider that, then graphene should be a topological insulator. And at the edge electrons should move in…
Z.Sun
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What's chiral about the Dirac points in graphene?
One of the main interesting properties of graphene is the appearance of Dirac points in its energy band structure, i.e. the presence of points where the valence and conduction bands meet at conical intersections at which the dispersion is (locally)…
Emilio Pisanty
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How is graphene a 2D substance?
How is graphene a 2D substance? It has length, width and some thickness to it, else it would be invisible. Why is it considered a 2D substance?
user793468
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Why do electrons in graphene behave as Dirac fermions near the Dirac points?
I've been learning about graphene, and I recently calculated the band structure for it using a nearest-neighbor tight-binding model for the $\pi$ electrons:
$$\varepsilon(\vec k)=\pm t\sqrt{3+2 \cos \left(\frac{\sqrt{3} k_x}{2}-\frac{3…
Manishearth
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How do Dirac fermions arise in graphene, and, what significance (if any) does this have for high-energy physics?
Graphene has a honeycomb lattice (in the absence of defects and impurities). By considering the low-energy limit of the half-filled Hubbard model used to model the strongly interacting electron gas we find that the low-energy quasiparticles obey the…
user346
10
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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 $E =\frac{3\hbar ta}{2}|k|$ where $t$ is the nearest-neighbor hopping…
user14717
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Why is Graphene Transparent?
Graphene is always in the news now a days and its key features are that it is; very strong, conductive and transparent. It is so transparent that each layer of graphene will only absorb 2% of Light passing through it.
But what is it about the…
zordman
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Graphene as optical and UV mirrors
One usually hears about graphene as a good thermal conductor, and good light absorber due to its tunable bandgap properties. But i haven't heard about its aplicability as an optical mirror. In fact, mostly the opposite is true: the optical…
lurscher
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Can we wrap vacuum aerogel with graphene to create a floating brick?
While I heard that we cannot make aerogel float in the air because air would fill the space inside
Then I just think that, why we don't seal it with something and then we would have lighter than air brick that might be used to build floating…
Thaina
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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.
What is the significance of this in condensed…
leongz
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Why electrons are relativistic in Graphene and non relativistic in vacuum?
If a free region in space has a potential difference of one volt, an electron in this region will acquire kinetic energy of 1 eV. Its speed will be much smaller than the speed of light hence it will be a non relativistic electron.
On the other hand…
Revo
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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 all about the transmission of an electron through…
hyd
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Why a mono-atomic crystal layer (2D) can't be stable?
According to Peierls and Landau, 2D crystals were thermodynamically unstable. They can't exist!
Of course, this theory was disapproved in 2004 (example: graphene).
What is the general definition of stability of a general system?
What is the…
aayyachi
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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 two 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 time symmetry leads to a quantum hall state. The…
sreeram
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