
Graphene becomes superconductive - jonbaer
https://www.tohoku.ac.jp/en/news/research/graphene_becomes_superconductive.html
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tedsanders
So far, most of the comments are lamenting that the superconducting
temperature of 4 K is uselessly low. That's true, but beside the point.

The point of superconducting graphene is _not_ to use it as a general purpose
superconductor where the goal is to have the highest Tc possible. The point of
superconducting graphene is that graphene's electrons flow in a way that's
very different from most materials.

In most materials, if you apply a voltage, the electrons will speed up (F=MA,
Newton's second law). This how a voltage drives electrons into your computer.

However, because of its crystal structure, graphene is different. In graphene,
electrons always travel at a constant speed, no slower and no faster. This
feature of graphene is also why its electrons are sometimes called massless
(despite not being truly massless). Their motion is analogous to photons,
which always travel at a constant speed. And because these electrons travel
like photons instead of electrons, it has a bunch of consequences in solid
state physics and electronics.

The importance of superconducting graphene is that we now have a new variety
of superconducting electrons to study.

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dnadler
Does this mean that the electrons experience infinite acceleration? I know
very little about graphene, but this seems to violate some basic laws of
physics. Do the electrons actually behave this way? Or is this description of
constant velocity electrons simply a close approximation/good analogy for what
is actually happening?

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DarkLinkXXXX
If anyone would like to read the journal article, it can be downloaded from
library genesis.

[http://libgen.io/scimag/index.php?s=10.1021%2Facsnano.5b0784...](http://libgen.io/scimag/index.php?s=10.1021%2Facsnano.5b07848&journalid=&v=&i=&p=&redirect=1)

~~~
mnl
Well... fortunately we have arXiv for open access e-print repository. This is
what you should quote:

[http://arxiv.org/abs/1508.07079](http://arxiv.org/abs/1508.07079)

I don't know if you are aware of this but there are many scientists out there
that do need the site you've mentioned in order to function. This kind of
exposure is going to kill their chances sooner than expected. The first rule
of Fight Club is: You do not talk about Fight Club.

~~~
DarkLinkXXXX
I must disagree. Unlike it's predecessors, such as textz, gigapedia, and
library.nu, (these are from before my time, so correct me if I'm wrong),
library genesis is healthily mirrored, and everything is torrented. Any
attempt to assail it will simply ensure its resilience in my opinion.

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callesgg
4K is not very useful, but it is progress non the less.

[https://en.wikipedia.org/wiki/List_of_superconductors](https://en.wikipedia.org/wiki/List_of_superconductors)

~~~
hendler
Highest listed there 39K
[https://en.wikipedia.org/wiki/Magnesium_diboride](https://en.wikipedia.org/wiki/Magnesium_diboride)
Doesn't mention others at [https://en.wikipedia.org/wiki/High-
temperature_superconducti...](https://en.wikipedia.org/wiki/High-
temperature_superconductivity) like
[https://en.wikipedia.org/wiki/Hydrogen_sulfide](https://en.wikipedia.org/wiki/Hydrogen_sulfide)
More at [https://en.wikipedia.org/wiki/Room-
temperature_superconducto...](https://en.wikipedia.org/wiki/Room-
temperature_superconductor)

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biot
Do we know enough about physics at the atomic level to be able to predict and
simulate these combinations of materials? Or do we still have no clue and it's
left to experiment to be able to validate material design?

~~~
Wingman4l7
Well, we know a lot about the crystal structures of several high-temperature
superconducting compounds. You could always make an educated guess of a new
one based on these and then test it for the Meissner effect.

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msie
At a low enough temperature (< 4K) ...

~~~
TTPrograms
I thought there were already demonstrations of superconductivity in graphene
at higher temperatures with other dopants (I think water IIRC).

~~~
sp332
Well, this effect was discovered last year
[http://cleantechnica.com/2015/09/10/single-layer-graphene-
su...](http://cleantechnica.com/2015/09/10/single-layer-graphene-
superconductor/) (at ~5K). The new breakthrough seems to be in manufacturing.

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kondro
Even Lead is superconductive at 7.2K.

~~~
noobermin
Someone explain this to me like I'm an undergraduate in Physics, why is this
significant then, just because it is Graphene?

~~~
tly
Metal just conducts while a semiconductor is like a switch that you can turn
on and off. Since graphene is a semiconductor it is more useful for creating
faster devices such as transistors.

~~~
tedsanders
A fair number of semiconductors superconduct too (such as SrTiO3). The notable
thing about graphene superconductivity is graphene's electrons, not its
ability to semiconduct. Because of graphene's crystal structure, electrons
propelled by a voltage will travel at constant speed, rather than
accelerating. In this sense, the electrons are 'massless' (photons are
massless, so they always travel at the speed of light and cannot be
accelerated).

~~~
noobermin
>electrons propelled by a voltage will travel at constant speed

You mean like Ohm's law with a constant electric field?

~~~
tedsanders
No, not like that. When electrons travel in a regular conductor, they have a
distribution of speeds. Ohm's law just describes their average behavior.

Just in case I misunderstood your question, I will say a few more things:

Ohm's law applies to both graphene and regular conductors.

In graphene, electrons have only one speed, but they can still move in any
direction. In a regular conductor, electrons have many speeds and move in any
direction.

In either case, with no electric field applied, the average velocity of
electrons will be zero. But with an electric field applied, the average
velocity of electrons will be non-zero. And in both cases, the average
velocity is proportional to the applied electric field, meaning that the
material can be described by concepts like resistance and electron mobility.

The key difference is that graphene has electrons with one speed and a
distribution of directions, whereas regular conductors have electrons with a
distribution of speeds and a distribution of directions.

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cshimmin
Psh, Jan Hendrik Schön showed in 2001 that carbon is superconducting at high
temperatures. Just kidding; he was a fraud, but it's a fascinating story:
[https://en.wikipedia.org/wiki/Schön_scandal](https://en.wikipedia.org/wiki/Schön_scandal)

~~~
77pt77
Totally fabricated and the other authors suffered no consequences.

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mikeyouse
Ignorant question but could this be useful for companies like D-wave who are
trying to build quantum machines? They're cooled to well below the
superconducting temperature as it is.. I guess I'm not sure what function the
graphene semiconductors serve.

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tempodox
When I read the title I thought at first it was new marketing speak for a
startup cashing a humongous funding round.

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dajomu
The temperature of deep space is 2.7K, so could these low temperature
superconductors have easier application there?

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kennysmoothx
Can someone please Explain This Like I'm 5 - The potential Graphene has when
compared to the Lithium batteries we have in the market today, and if Graphene
is going to make it's way into our batteries any time in the near future?

Thanks

\-- EDIT --

Pardon my ignorance! It seems I was very confused about the topic in question,
and mistakenly asked about super capacitors. Thanks for pointing it out!

~~~
ldom66
I think this is not linked with battery storage. Superconductivity allows a
material to conduct electrons without any resistance, thus losing less energy
and generating less heat. I could be wrong though, I am no expert.

~~~
nalllar
You can use superconductors for energy storage. An inductor stores energy, but
can not be used for long-term energy storage due to resistance. A
superconducting inductor can be used to store energy, as there is no loss due
to resistance.

[https://en.wikipedia.org/wiki/Superconducting_magnetic_energ...](https://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage)

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xyzzy4
My prediction for the year 2100: many more articles about graphene, little to
no real world usage growth.

