65 nanotimes News in Brief
In Physical Review Letters, Kwanpyo Kim and colleagues at the University of California, Berkeley, have cataloged the experimental Raman spectra of a series of graphene double layers where the top layer is rotated with respect to the bottom layer in one degree increments, up to a 30 degree mismatch. Kim et al. fabricated the double-layered samples by first growing single layers of polycrystalline graphene and then stacking them together. Transmission electron microscopy allowed the group to precisely measure the relative angle between the two layers. © Sami Mitra/APS
Kwanpyo Kim, Sinisa Coh, Liang Z. Tan, William Regan, Jong Min Yuk, Eric Chatterjee, M. F. Crommie, Marvin L. Cohen, Steven G. Louie, and A. Zettl: Raman Spectroscopy Study of Rotated Double-Layer Graphene: Misorientation-Angle Dependence of Electronic Structure, In: Physical Review Letters, Volume 108, Issue 24, June 15, 2012, Article 246103 [6 pages], DOI:10.1103/PhysRevLett.108.246103:
http://dx.doi.org/10.1103/PhysRevLett.108.246103
A team of scientists at Berkeley Lab and the University of California at Berkeley (US), led by Alessandra Lanzara in collaboration with Joseph Orenstein and Dung-Hai Lee of the Lab's Materials Sciences Division (MSD), has used a new and uniquely powerful tool to attack some of the biggest obstacles to understanding the electronic states of high-temperature superconductors – and how they may eventually be put to practical use. The team reports their research using ultrafast laser ARPES (ultrafast Angle-Resolved PhotoEmission Spectroscopy) in the journal Science. "The mechanism binding Cooper pairs together in high-Tc superconductors is one of the great mysteries in materials science," says Christopher Smallwood, a member of Lanzara‘s group and first author of the Science paper. "What we‘ve done with ultrafast laser ARPES is to start with a high-Tc superconductor called Bi2212 and cool it to well below the critical temperature where it becomes superconducting."
Christopher L. Smallwood, James P. Hinton, Christopher Jozwiak, Wentao Zhang, Jake D. Koralek, Hiroshi Eisaki,
Dung-Hai Lee, Joseph Orenstein, Alessandra Lanzara: Tracking Cooper Pairs in a Cuprate Superconductor by Ultrafast Angle-Resolved Photoemission, In: Science
Magazine, June 01, 2012, Vol. 336, No. 6085, Pages 1137-1139, DOI:10.1126/science.1217423:
http://dx.doi.org/10.1126/science.1217423
http://www.nature.com/nphys/journal/v7/n10/full/nphys2027.html
Scientists and engineers at the University of Wisconsin-Milwaukee (UWM) have discovered an entirely new carbon-based material that is synthesized from graphene. The discovery, which the researchers are calling "Graphene Monoxide (GMO)," pushes carbon materials closer to ushering in next-generation electronics.
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