Key property of graphene sustained over wide ranges of density and energy

Nov 15, 2012

(Phys.org)—A collaboration led by researchers from the NIST Center for Nanoscale Science and Technology  has shown for the first time that charge carriers in graphene continue to behave as massless particles, like photons, over wider ranges of both density and energy than previously measured or modeled.

Graphene, a single layer of , is a material of great scientific and technological interest in part because it conducts electrons at high speed.  However, in order for graphene to achieve its promise as a component of future electronic devices, it is important to understand at a fundamental level how charge carriers in the material interact with each other.  The researchers used scanning tunneling spectroscopy measurements of the magnetic quantum energy levels of the graphene charge carriers to determine the changes in velocity of the

Using a CNST-developed technique called "gate mapping scanning tunneling spectroscopy," the researchers measured the energy levels as they changed the density of the carriers in the graphene by applying different potentials between a conducting gate and the two-dimensional .  They established that the graphene carriers retain a proportional relationship between energy and momentum—a "linear dispersion" characteristic of —across an unexpectedly broad range of energies and densities, from electrons to holes.  They were also able to show that when the density of carriers in graphene is lowered, the effect of each electron on other electrons increases, resulting in higher velocities than expected. 

These surprising results are important both for understanding the physics of future graphene devices and because they will help guide the development of more accurate of the interactions between electrons in two-dimensional systems.

Explore further: The rub with friction: Researchers uncover new rules of friction at microscopic level

More information: Chae, J. et al., Renormalization of the graphene dispersion velocity determined from scanning tunneling spectroscopy. Physical Review Letters 109, 116802 (2012).

add to favorites email to friend print save as pdf

Related Stories

The secrets of tunneling through energy barriers

Nov 07, 2011

Electrons moving in graphene behave in an unusual way, as demonstrated by 2010 Nobel Prize laureates for physics Andre Geim and Konstantin Novoselov, who performed transport experiments on this one-carbon-atom-thick material. ...

Graphene Yields Secrets to Its Extraordinary Properties

May 14, 2009

(PhysOrg.com) -- Applying innovative measurement techniques, researchers from the Georgia Institute of Technology and the National Institute of Standards and Technology have directly measured the unusual energy ...

New technique controls graphite to graphene transition

Jul 02, 2012

(Phys.org) -- University of Arkansas physicists have found a way to systematically study and control the transition of graphite, the “lead” found in pencils, to graphene, one of the strongest, lightest ...

Two graphene layers may be better than one

Apr 27, 2011

(PhysOrg.com) -- Researchers at the National Institute of Standards and Technology have shown that the electronic properties of two layers of graphene vary on the nanometer scale. The surprising new results ...

Recommended for you

Glass coating improves battery performance

Mar 02, 2015

Lithium-sulfur batteries have been a hot topic in battery research because of their ability to produce up to 10 times more energy than conventional batteries, which means they hold great promise for applications ...

Semiconductor miniaturisation with 2D nanolattices

Feb 26, 2015

A European research project has made an important step towards the further miniaturisation of nanoelectronics, using a highly-promising new material called silicene. Its goal: to make devices of the future ...

Magnetic nanoparticles enhance performance of solar cells

Feb 25, 2015

Magnetic nanoparticles can increase the performance of solar cells made from polymers - provided the mix is right. This is the result of an X-ray study at DESY's synchrotron radiation source PETRA III. Adding ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.