Rensselaer Research ReviewWinter 2008
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graphene
Researchers at Rensselaer have developed a new method for controlling the conductive nature of graphene. Pictured is a rendering of two sheets of graphene, each with the thickness of just a single carbon atom, resting on top of a silicon dioxide substrate.
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Light-Speed Nanotech: Controlling the Nature of Graphene

Researchers at Rensselaer Polytechnic Institute have discovered a new method for controlling the nature of graphene, bringing academia and industry potentially one step closer to realizing the mass production of graphene-based nanoelectronics.

With help from an underlying substrate, researchers for the first time have demonstrated the ability to control the nature of graphene. Saroj Nayak, an associate professor in Rensselaer’s Department of Physics, Applied Physics, and Astronomy, along with Philip Shemella, a postdoctoral research associate in the same department, have determined that the chemistry of the surface on which graphene is deposited plays a key role in shaping the material’s conductive properties. The results are based on large-scale quantum mechanical simulations.

Results show that when deposited on a surface treated with oxygen, graphene exhibits semiconductor properties. When deposited on a material treated with hydrogen, however, graphene exhibits metallic properties.

“Depending on the chemistry of the surface, we can control the nature of the graphene to be metallic or semiconductor,” Nayak said. “Essentially, we are ‘tuning’ the electrical properties of material to suit our needs.” 

New Hybrid Nanostructures Detect Nanoscale Magnetism

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nanoclcusters
A rendering depicting the cobalt nanoclusters embedded in multi-walled carbon nanotubes.
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Researchers at Rensselaer Polytechnic Institute have developed and demonstrated a new method for detecting the magnetic behaviors of nanomaterials. They created a new process for creating a single multi-walled carbon nanotube that is embedded with cobalt nanostructures. The cobalt clusters measure from 1 nanometer to 10 nanometers. 

After a series of experiments, the research team has concluded that the electrical conductance of carbon nanotubes is sensitive enough to detect and be affected by trace amounts of magnetic activity, such as those present in the embedded cobalt nanostructures. It is believed to be the first instance of demonstrating the detection of magnetic fields of such small magnets using an individual carbon nanotube.

“Since the cobalt clusters in our system are embedded inside the nanotube rather than on the surface, they do not cause electron scattering and thus do not seem to impact the attractive conductive properties of the host carbon nanotube,” said Swastik Kar, research assistant professor in Rensselaer’s Department of Physics, Applied Physics, & Astronomy, who led the project. “From a fundamental point of view, these hybrid nanostructures belong to a new class of magnetic materials.” 

Potential applications for such a material include new generations of nanoscale conductance sensors, along with new advances in digital storage devices, spintronics, and selective drug delivery components.

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