11-11/12 :: November/December 2011

nanotimes News in Brief

Researchers from the London Centre for Nano- technology (LCN) have discovered electronic stri- pes, called ‘charge density waves’, on the surface of the graphene sheets that make up a graphitic superconductor. This is the first time these stripes have been seen on graphene, and the finding is likely to have profound implications for the exploi- tation of this recently discovered material, which scientists believe will play a key role in the future of nanotechnology.

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nanometer-scale stripes. This unexpected behavior demonstrates that the electrons can have a life of their own which is not connected directly to the un- derlying atoms. The results inspire many new direc- tions for both science and technology. For example, they suggest a new method for manipulating and encoding information, where binary zeros and ones correspond to stripes running from north to south and running from east to west respectively.

K.C. Rahnejat, C.A. Howard, N.E. Shuttleworth, S.R, Schofield, K. Iwaya, C.F. Hirjibehedin, Ch. Renner, G. Aeppli, M. Ellerby: Charge density waves in the graphene sheets of the superconductor CaC6, In: Nature Commu- nications, Vol. 2(2011), Article number: 558, November 29, 2011, DOI:10.1038/ncomms1574: http://dx.doi.org/10.1038/ncomms1574

Electronic stripes, called ‘charge density waves’, on the surface of a graphitic superconductor. © K.A. Rahnejat

The LCN team donated extra electrons to a gra- phene surface by sliding calcium metal atoms underneath it. One would normally expect these additional electrons to spread out evenly on the graphene surface, just as oil spreads out on water. But by using an instrument known as a scanning tunneling microscope, which can image individual atoms, the researchers have found that the extra electrons arrange themselves spontaneously into

Professor of Nanotechnology, Andrea Ferrari, and colleagues from the Engineering Department at the University of Cambridge have developed a me- thod of creating a graphene ink that can be used with a modified ink-jet printer. Graphene consists of a hexagonal lattice of carbon only one atom thick, and has great advantages over polymer inks because of its greater electron mobility and electri- cal conductivity.

F. Torrisi, T. Hasan, W. Wu, Z. Sun, A. Lombardo, T. Kulmala, G. W. Hshieh, S. J. Jung, F. Bonaccorso, P. J. Paul, D. P. Chu, A. C. Ferrari: Ink-Jet Printed Graphene Electronics, In: arXiv:1111.4970v1 [cond-mat.mtrl-sci]: http://arxiv.org/abs/1111.4970