January 5, 2012 — Rensselaer Polytechnic Institute (RPI) scientists used the Rensselaer Center for Nanotechnology Innovations (CCNI) supercomputer to study a promising form of graphene: graphene nanowiggles. Graphitic nanoribbons were segmented into several different surface structures (nanowiggles), which each produce highly different magnetic and conductive properties.
The scientists used computational analysis to study several different nanowiggle structures. The structures are named based on the shape of their edges: armchair, armchair/zigzag, zigzag, and zigzag/armchair. All of the nanoribbon-edge structures have a wiggly appearance like a caterpillar inching across a leaf. The team named the four structures nanowiggles and each wiggle produced exceptionally different properties.
|Figure. Graphene nanowiggles. Source: Rensselaer Polytechnic Institute (RPI).|
They found that the different nanowiggles produced highly varied bandgaps. Different nanowiggles exhibited up to five highly varied magnetic properties.
RPI calls the research a "blueprint" for scientists to pick out graphene nanostructures for various tasks or devices, based on bandgap and magnetic requirements. "We have created a roadmap that can allow for nanomaterials to be easily built and customized for applications from photovoltaics to semiconductors and, importantly, spintronics," Meunier said.
"Graphene nanomaterials have plenty of nice properties," said Vincent Meunier, the Gail and Jeffrey L. Kodosky ’70 Constellation Professor of Physics, Information Technology, and Entrepreneurship at Rensselaer, "but to date it has been very difficult to build defect-free graphene nanostructures," because the nanostructures are hard to reproduce.
A group led by scientists at EMPA, Switzerland, recently discovered the graphene nanowiggle. These particular nanoribbons are formed using a bottom-up approach, since they are chemically assembled atom by atom. Standard graphene material design involves breaking down an existing material into new structures, which can lead to imperfect, zig-zag edges.
Graphene nanowiggles can easily and quickly be produced in very long and clean structures, Meunier reports, and easily modified to display exceptional electrical conductive properties. Meunier’s team is working to dissect the nanowiggles to better understand possible future applications. Nanowiggle properties are "even more surprising than previously thought," Meunier said.
By using CCNI, Meunier was able to complete sophisticated calculations in a few months, which would have taken over a year without supercomputing.
The findings were published in the journal Physical Review Letters in a paper titled “Emergence of Atypical Properties in Assembled Graphene Nanoribbons.” Access it at http://prl.aps.org/abstract/PRL/v107/i13/e135501.
Learn more about Rensselaer Polytechnic Institute at www.rpi.edu.