Promise of graphene

Last Updated 11 October 2010, 13:32 IST

A pair of Russian-born physicists working at the University of Manchester in England have won the Nobel Prize in Physics for investigating the remarkable properties of ultrathin carbon flakes known as graphene. The physicists are Andre Geim, 51 and Konstantin Novoselov, 36.

Graphene is a form of carbon in which the atoms are arranged in a flat hexagon lattice like microscopic chicken wire, a single atom thick. It is not only the thinnest material in the world but also one of the strongest and hardest. Among its other properties, graphene is able to conduct electricity as well as copper does and to conduct heat better than any other known material, and it is practically transparent. Physicists say that it could eventually rival silicon as a basis for computer chips, serve as a sensitive pollution-monitoring material, improve flat-screen televisions and enable the creation of new materials and novel tests of quantum weirdness.

The Royal Academy said, “Carbon, the basis of all known life on Earth, has surprised us once again.” Graphene is related to two other forms of carbon that have generated intense interest in recent years: buckyballs, which are soccer-ball arrangements of carbon atoms, and nanotubes, which are rolled-up sheets of carbon atoms. It was long thought, however, that an essentially two-dimensional sheet of carbon atoms would be unstable and would warp or fold up.

Geim and Novoselov succeeded in creating flakes of graphene by peeling them off piles of graphite – the material that is in a pencil lead – using Scotch tape. Geim, who was born in Sochi, Russia, and is now a Dutch citizen, studied at the Moscow Physical-Technical Institute and was awarded a Ph D at the Institute of Solid State Physics in Chernogolovka in 1987.

It was at the University of Nijmegen in the Netherlands that he connected with Novoselov, who was born in Nizhny Tagil and became Geim’s graduate student in the Netherlands. When Geim moved to Manchester, he took Novoselov with him; Novoselov is now a British and Russian citizen. The graphene creation originated in what Geim and Novoselov call “Friday evening” experiments, crazy things that might or might not work out. In one of them, Geim managed to levitate a frog in a magnetic field, for which he won an Ig Nobel – a parody award for “improbable research” – in 2000.

Of Scotch tape and graphite
On another occasion they produced a “gecko tape” that mimicked the way geckos and Spider-Man can walk on the ceiling. The work on graphene arose from the pair’s desire to investigate the electrical properties of graphite. To do that, they needed very thin pieces, which they first tried to produce by filing down graphite crystals, with no luck. Then a technician showed them how graphite was cleaned before being observed in a scanning tunneling microscope by peeling layers off with Scotch tape.

The scientists placed a flake of graphite on some tape and then by folding the tape over it again and again, gradually cleaved it thinner and thinner until it was only one atom thick. The Scotch tape technique is still used, although the Manchester researchers have switched to a different tape. Geim once described the process as “very nonboffinlike” – using British slang for a research scientist – and an example of how you could do great experiments even if you did not have the resources of Harvard or Cambridge. “You can still do something amazing,” he said. The first two papers on graphene were published in Science and online in 2004. Three more appeared in 2005.

Since then, the Swedish Academy said, “research in this area has literally exploded,” producing a growing number of papers about graphene, its amazing properties and its promise. If scaled up to the thickness of plastic refrigerator wrap, a sheet of graphene stretched over a coffee cup could support the weight of a truck bearing down on a pencil point, according to tests conducted by two Columbia University researchers, Jeffrey Kysar and James Hone. Graphene also made it into popular culture, being featured in an episode of the CBS sitcom “The Big Bang Theory” in February. David Saltzberg, a physicist at the University of California, Los Angeles, who serves as the show’s scientific consultant, called graphene “the greatest thing since sliced pencil lead.”

Joseph Stroscio of the National Institute of Standards and Technology in Gaithersburg, Md., said that he had been skeptical initially about the promise of graphene, but “each year I’m surprised to see all the new experiments showing new potential applications ranging from electronic devices and chemical sensors to composite materials.”  

Properties of high-energy physics
He said the speed with which the prize was awarded to Geim and Novoselov was a reflection of the excitement about possible applications and the new physics experiments that could be performed with graphene. Because of the hexagonal structure, electrons moving through graphene do not act like the billiard balls of classic physics, bumping from atom to atom, but rather like massless waves obeying the laws of relativistic physics. As a result, Stroscio said, graphene has properties that could be seen before only in high-energy physics. “That’s what started the frenzy,” he said. Instead of needing a particle accelerator, “you can do relativistic experiments on a table top.”

The new laureates both say they are in graphene for the physics, but the field is getting crowded. Thousands of researchers are involved in graphene now, Geim said in the interview on the Nobel website, and he keeps looking for a new corner of it to explore. “I’m very proud when I scoop someone, but I have been scooped myself.” He is the first scientist to win both a Nobel and an Ig Nobel. He said he was happy to have both because the Ig Nobel was given “for something that forces people to smile.” Noloselov, one of the youngest scientists ever to win a Nobel, said he was trying not to think about what it would mean for his career. As the telephone rang in the background, he said: “I had quite a bit of plans for today. It looks like they are all ruined now.”

(Published 11 October 2010, 13:32 IST)

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