Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Particle Works creates range of high performance quantum dots February 23rd, 2017

GLOBALFOUNDRIES Announces Availability of 45nm RF SOI to Advance 5G Mobile Communications: Optimized RF features deliver high-performance solutions for mmWave beam forming applications in 5G smartphones and base stations February 22nd, 2017

EmTech Asia breaks new barriers with potential applications of space exploration with NASA and MIT February 22nd, 2017

JPK selects compact tensile stage from Deben for their NanoWizard® AFM platform to broaden capabilities for materials characterisation February 22nd, 2017

Chip Technology

GLOBALFOUNDRIES Announces Availability of 45nm RF SOI to Advance 5G Mobile Communications: Optimized RF features deliver high-performance solutions for mmWave beam forming applications in 5G smartphones and base stations February 22nd, 2017

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Particles from outer space are wreaking low-grade havoc on personal electronics February 19th, 2017

Liquid metal nano printing set to revolutionize electronics: Creating integrated circuits just atoms thick February 18th, 2017

Discoveries

Molecular phenomenon discovered by advanced NMR facility: Cutting edge technology has shown a molecule self-assembling into different forms when passing between solution state to solid state, and back again - a curious phenomenon in science - says research by the University of Wa February 22nd, 2017

Tiny nanoclusters could solve big problems for lithium-ion batteries February 21st, 2017

Oxford Instruments announces Dr Brad Ramshaw of Cornell University, as winner of the 2017 Lee Osheroff Richardson Science Prize February 20th, 2017

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

Announcements

Particle Works creates range of high performance quantum dots February 23rd, 2017

GLOBALFOUNDRIES Announces Availability of 45nm RF SOI to Advance 5G Mobile Communications: Optimized RF features deliver high-performance solutions for mmWave beam forming applications in 5G smartphones and base stations February 22nd, 2017

EmTech Asia breaks new barriers with potential applications of space exploration with NASA and MIT February 22nd, 2017

JPK selects compact tensile stage from Deben for their NanoWizard® AFM platform to broaden capabilities for materials characterisation February 22nd, 2017

Quantum nanoscience

The speed limit for intra-chip communications in microprocessors of the future January 23rd, 2017

First experimental proof of a 70 year old physics theory: First observation of magnetic phase transition in 2-D materials, as predicted by the Nobel winner Onsager in 1943 January 6th, 2017

Quantum simulation technique yields topological soliton state in SSH model January 3rd, 2017

Diamonds are technologists' best friends: Researchers from the Lomonosov Moscow State University have grown needle- and thread-like diamonds and studied their useful properties December 30th, 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