Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Critical questions: Ripples in the structure of graphene could be the key to understanding its unusual characteristics

Figure 1: Graphene consists of a single layer of carbon atoms arranged in a hexagonal array. Its structure and two-dimensional nature gives rise to its unique and potentially useful electronic characteristics.

source: Wikimedia/Thomas Szkopek
Figure 1: Graphene consists of a single layer of carbon atoms arranged in a hexagonal array. Its structure and two-dimensional nature gives rise to its unique and potentially useful electronic characteristics.

source: Wikimedia/Thomas Szkopek

Abstract:
Graphene is a two-dimensional material that consists of a hexagonal array of carbon just one atom thick (Fig. 1). Although it is essentially just a single sheet of graphite, its properties are remarkable and unique. Notably, its charge carriers behave like massless relativistic particles, and move at a speed of just 300 times less than the speed of light—many times more quickly than in silicon. This makes graphene a potentially attractive alternative to silicon as future computer chips.

Critical questions: Ripples in the structure of graphene could be the key to understanding its unusual characteristics

Japan | Posted on October 19th, 2008

Many questions remain about graphene. A numerical study conducted by an international team of physicists including Akira Furusaki of RIKEN's Advanced Science Institute in Wako, attempts to explain the unusual quantum Hall effect that arises in graphene, and the influence of disorder of its 2D structure on its behavior1.

The quantum Hall effect occurs in metal-like systems whose electrons are confined to move only in a two-dimensional plane. It is characterized by the emergence of plateaus in the conductance measured transverse to the flow of current through the system—known as the Hall conductance—when a large magnetic field is applied through the plane.

In graphene, the quantum Hall effect is subtly different to that in other 2D systems. Normally, the Hall conductance begins at zero and increases in exact increments, described as e2/h, with increasing magnetic field or charge concentration. In graphene, however, the conductance changes in multiples of 4e2/h and the whole characteristic is shifted by half this value.

Moreover, in most systems it is usually destroyed by disorder or by thermal fluctuations at temperatures much above absolute zero. But in graphene, it is remarkably insensitive to both, with the Hall plateaus around zero conductivity evident all the way up to room temperature.

The simulations performed by Furusaki and colleagues suggest that the robustness of the quantum Hall effect in graphene arises as a result of the relativistic nature of its charge carriers. Under certain amounts of disorder, the wavefunctions of zero-energy carrier states do not become localized in the same way as those of nonrelativistic carriers in conventional quantum Hall systems would. The researchers argue that the occurrence of such nonlocalized states—known as critical states—could explain why the initial Hall plateaus occur at +/- 2e2/h, rather than at zero before increasing in multiples of 4e2/h. Moreover, they argue that the expected occurrence of ripples in graphene's structure could be enough to cause these nonlocalized states to emerge.
Reference

1. Nomura, K., Ryu, S., Koshino, M., Mudry, C. & Furusaki, A. Quantum Hall effect of massless Dirac fermions in a vanishing magnetic field. Physical Review Letters 100, 246806 (2008).

The corresponding author for this highlight is based at the RIKEN Condensed Matter Theory Laboratory

####

For more information, please click here

Copyright © Riken

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Article

Related News Press

News and information

Automating DNA origami opens door to many new uses: Like 3-D printing did for larger objects, method makes it easy to build nanoparticles out of DNA May 30th, 2016

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Chip Technology

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Dartmouth team creates new method to control quantum systems May 24th, 2016

Attosecond physics: A switch for light-wave electronics May 24th, 2016

Discoveries

Automating DNA origami opens door to many new uses: Like 3-D printing did for larger objects, method makes it easy to build nanoparticles out of DNA May 30th, 2016

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Announcements

Automating DNA origami opens door to many new uses: Like 3-D printing did for larger objects, method makes it easy to build nanoparticles out of DNA May 30th, 2016

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Quantum nanoscience

Researchers demonstrate size quantization of Dirac fermions in graphene: Characterization of high-quality material reveals important details relevant to next generation nanoelectronic devices May 20th, 2016

Graphene: A quantum of current - When current comes in discrete packages: Viennese scientists unravel the quantum properties of the carbon material graphene May 20th, 2016

Technique improves the efficacy of fuel cells: Research demonstrates a new phase transition from metal to ionic conductor May 18th, 2016

Theorists smooth the way to modeling quantum friction: New paradigm offers a strategy for solving one of quantum mechanics' oldest problems May 18th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic