Tuesday, October 5, 2010


The Nobel Prize in Physics today was awarded for the discovery of Graphene, a single layer carbon sheet. Back in this post in 2009, I mentioned that this was a hot topic at the APS march meeting.

It turns out that the whole trick to producing graphene is Scotch-Tape. If you take a piece of tape and you lightly touch it to graphite (pencil lead) you frequently will pull off just a single layer of carbon. Pretty cool. (This trick for pulling off thin layers with tape has been known for many years to chemists and material scientists).

Back in this post when I was taking bets for last year's Nobel prize, I made the following statement suggesting that it was not actually deserving of the prize:

Reuters proposes Geim and Novoselov (22%) for the discovery of graphene (carbon sheets) and Ijima (14%) narrowly behind for the discovery of nanotubes (carbon sheets rolled up into a tube). Not that I am opposed to carbon but…

I will remind everyone that Buckyballs, yet another form of Carbon, already won the Nobel prize recently – but in chemistry, not physics. I will also remind everyone that not every molecule made of carbon deserves an immediate Nobel prize. I know that the Carbonists have been lobbying hard, and admittedly both nanotubes and graphene are pretty cool. But I don’t think they are so overwhelmingly cool that they need a Nobel prize just yet. And if the lessons of Buckyballs are anything to learn from, we should expect that the hype will far outweigh the actual usefulness of, or interest in, the stuff in the long run.

I'm amused to see that Doug, over at nanoscale views seems to have a similar opinion.

On the flip-side, graphene is pretty cool stuff. If any fraction of the hype turns out to be true in 10 years, then I would certainly support the prize (and simultaneously eat my words). But from the buckeyball experience I would have thought the Nobel committee might have waited a bit longer on this one. It isn't like the winners are old geezers about to croak who have to be given the prize now since they are not going to survive until next year.

So there you have it... the Nobel prize won with Scotch-tape.


HM said...

Well, the graphene "discovery" has stimulated much development. Even the discovery of topological insulators (Kane and Mele 2005) was indirectly motivated by this experiment. In the end, isn't the Impact of a discovery on physics, more important that usefulness in the long run?

By the way, is the fractional quantum Hall effect in graphene special in any way, compared to other materials? Do you know if the 5/2 state has been observed there?

Steve said...

Good point regarding topological insulators --- although that likely would have been discovered soon thereafter considering the interest in spin-hall anyway.

FQHE is not too special in graphene (and it has not been observed at 5/2. Only 1/3 and maybe 2/3 I think).

There are a few things that are a bit different in graphene

(1) the electron gas is more "exposed" than in GaAs where the electron gas is buried. This means that (a) the effective dielectric constant is much smaller than in GaAs, so the interaction energy scale is much larger. (b) You might be able to do better scanned probe experiments because the probe can get right up to the surface

(2) The mixing of the landau levels means the form factors for interaction are slightly different. This means that certain fractions may be seen here that are not seen in GaAs or vice versa. In fact, as far as seeing exotic states goes --it looks likely that graphene is not as good as GaAs -- even if it had similar mobility. (Ex, Moore-Read 5/2 state is probably not stable)

(3) There is a putative four-fold degeneracy of each landau level (2-fold for LL0). This means you could in principle get interesting skyrmion and spin structures.

HM said...

I think you are right regarding topological insulators. If I'm not wrong, Shoucheng Zhang and his group proposed a version of quantum spin Hall effect at around the same time as Kane and Mele, but inspired by the spin Hall effect rather than graphene.

Thank you for the information regarding FQHE in graphene, very interesting.