Graphene research at Cal: Close, but no Nobel

Graphene, a single layer of carbon atoms

Fans of the Nobel Prize in Physics know that this year’s honors went to a pair of U.K.-based researchers for the discovery of graphene, a.k.a., The World’s Thinnest Material.  While neither winner has a significant connection to UC Berkeley (the last Cal professor to win the physics Nobel was George Smoot in 2006), many here in the physics department can rightly claim at least some stake in this year’s prize.  That’s because graphene’s discovery in 2004 sparked a huge burst of high-impact research around the globe, much of which has been influenced by the work of Berkeley scientists.

For example, in 2007 Professor Alessandra Lanzara’s group published a paper demonstrating a new way to modify graphene’s electrical properties that makes it more useful for high-performance computation devices.  The paper has since been cited nearly 300 times – that’s an average of almost two citations per week – and that’s just one of her group’s many influential graphene publications.

Professors Marvin Cohen and Steven Louie are another pair of Berkeley physicists involved in high profile graphene-related projects.  They have co-authored several influential papers on the theory of graphene nanoribbons, including a 2006 Nature paper on their magnetic properties that has received over 500 citations and another on their electronic and optical properties with over 400 citations.  Again, these citation numbers are especially impressive because they have all come in a period of just over four years.

Acrobats form a human version of graphene

More recently, Professor Michael Crommie’s group has put graphene sheets under a powerful microscope to experimentally observe intriguingly-named effects like charge puddles and nanobubbles.  Likewise, Professor Alex Zettl has employed novel imaging techniques to monitor dynamic processes in graphene like the movement of individual atoms. Both of their experimental breakthroughs are particularly interesting to engineers, who can now think about how to harness these exotic physical behaviors for practical applications.

Yet another breakthrough came last year, when Professor Feng Wang’s group demonstrated that the optical properties of bilayer graphene (a.k.a., The World’s Second Thinnest Material?) are electrically tunable. That means the color of light emitted or absorbed by bilayer graphene can be changed without modifying its physical structure at all — a highly desirable trait for next-generation computation and communication devices.

Alas, they don’t give the prize to more than three individuals at a time, so the graphene prize could only be awarded to its original discoverers. But if you ever run into Andre Geim or Konstantin Novoselov, be sure to tell them “you’re welcome” from the UC Berkeley scientific community.

For more on graphene-related work at Cal, visit the homepages for the groups I’ve mentioned above or, better yet, track down all the other groups whose work on graphene I omitted for lack of space.

ResearchBlogging.orgZhou SY, Gweon GH, Fedorov AV, First PN, de Heer WA, Lee DH, Guinea F, Castro Neto AH, & Lanzara A (2007). Substrate-induced bandgap opening in epitaxial graphene. Nature Materials, 6 (10), 770-5 PMID: 17828279

Son YW, Cohen ML, & Louie SG (2006). Half-metallic graphene nanoribbons. Nature, 444 (7117), 347-9 PMID: 17108960

Son YW, Cohen ML, & Louie SG (2006). Energy gaps in graphene nanoribbons. Physical Review Letters, 97 (21) PMID: 17155765

Zhang, Y., Brar, V., Girit, C., Zettl, A., & Crommie, M. (2009). Origin of spatial charge inhomogeneity in graphene Nature Physics, 5 (10), 722-726 DOI: 10.1038/nphys1365

Levy N, Burke SA, Meaker KL, Panlasigui M, Zettl A, Guinea F, Castro Neto AH, & Crommie MF (2010). Strain-induced pseudo-magnetic fields greater than 300 tesla in graphene nanobubbles. Science, 329 (5991), 544-7 PMID: 20671183

Girit, C., Meyer, J., Erni, R., Rossell, M., Kisielowski, C., Yang, L., Park, C., Crommie, M., Cohen, M., Louie, S., & Zettl, A. (2009). Graphene at the Edge: Stability and Dynamics Science, 323 (5922), 1705-1708 DOI: 10.1126/science.1166999

Zhang Y, Tang TT, Girit C, Hao Z, Martin MC, Zettl A, Crommie MF, Shen YR, & Wang F (2009). Direct observation of a widely tunable bandgap in bilayer graphene. Nature, 459 (7248), 820-3 PMID: 19516337