Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Graphene exhibits bizarre new behavior well-suited to electronic devices

Scanning tunneling microscope image of a single layer of graphene on platinum with four nanobubbles at the graphene-platinum border and one in the patch interior. The inset shows a high-resolution image of a graphene nanobubble and its distorted honeycomb lattice due to strain in the bubble. (Crommie lab, UC Berkeley image)
Scanning tunneling microscope image of a single layer of graphene on platinum with four nanobubbles at the graphene-platinum border and one in the patch interior. The inset shows a high-resolution image of a graphene nanobubble and its distorted honeycomb lattice due to strain in the bubble. (Crommie lab, UC Berkeley image)

Abstract:
Graphene, a sheet of pure carbon heralded as a possible replacement for silicon-based semiconductors, has been found to have a unique and amazing property that could make it even more suitable for future electronic devices.

Graphene exhibits bizarre new behavior well-suited to electronic devices

Berkeley, CA | Posted on July 30th, 2010

Physicists at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL) have found that when graphene is stretched in a specific way it sprouts nanobubbles in which electrons behave in a bizarre way, as if they are moving in a strong magnetic field.

Specifically, the electrons within each nanobubble segregate into quantized energy levels instead of occupying energy bands, as in unstrained graphene. The energy levels are identical to those that an electron would occupy if it were moving in circles in a very strong magnetic field, as high as 300 tesla, which is bigger than any laboratory can produce except in brief explosions, said Michael Crommie, professor of physics at UC Berkeley and a faculty researcher at LBNL. Magnetic resonance imagers use magnets less than 10 tesla, while the Earth's magnetic field at ground level is 31 microtesla.

"This gives us a new handle on how to control how electrons move in graphene, and thus to control graphene's electronic properties, through strain," Crommie said. "By controlling where the electrons bunch up and at what energy, you could cause them to move more easily or less easily through graphene, in effect, controlling their conductivity, optical or microwave properties. Control of electron movement is the most essential part of any electronic device."

Crommie and colleagues report the discovery in the July 30 issue of the journal Science.

Aside from the engineering implications of the discovery, Crommie is eager to use this unusual property of graphene to explore how electrons behave in fields that until now have been unobtainable in the laboratory.

"When you crank up a magnetic field you start seeing very interesting behavior because the electrons spin in tiny circles," he said. "This effect gives us a new way to induce this behavior, even in the absence of an actual magnetic field."

Among the unusual behaviors observed of electrons in strong magnetic fields are the quantum Hall effect and the fractional quantum Hall effect, where at low temperatures electrons also fall into quantized energy levels.

The new effect was discovered by accident when a UC Berkeley postdoctoral researcher and several students in Crommie's lab grew graphene on the surface of a platinum crystal. Graphene is a one atom-thick sheet of carbon atoms arranged in a hexagonal pattern, like chicken wire. When grown on platinum, the carbon atoms do not perfectly line up with the metal surface's triangular crystal
structure, which creates a strain pattern in the graphene as if it were being pulled from three different directions.

The strain produces small, raised triangular graphene bubbles 4 to 10 nanometers across in which the electrons occupy discrete energy levels rather than the broad, continuous range of energies allowed by the band structure of unstrained graphene. This new electronic behavior was detected spectroscopically by scanning tunneling microscopy. These so-called Landau levels are reminiscent of the quantized energy levels of electrons in the simple Bohr model of the atom, Crommie said.

The appearance of a pseudomagnetic field in response to strain in graphene was first predicted for carbon nanotubes in 1997 by Charles Kane and Eugene Mele of the University of Pennsylvania. Nanotubes are a rolled up form of graphene.

Within the last year, however, Francisco Guinea of the Instituto de Ciencia de Materiales de Madrid in Spain, Mikhael Katsnelson of Radboud University of Nijmegen, the Netherlands, and A. K. Geim of the University of Manchester, England predicted what they termed a pseudo quantum Hall effect in strained graphene . This is the very quantization that Crommie's research group has experimentally observed. Boston University physicist Antonio Castro Neto, who was
visiting Crommie's laboratory at the time of the discovery, immediately recognized the implications of the data, and subsequent experiments confirmed that it reflected the pseudo quantum Hall effect predicted earlier.

"Theorists often latch onto an idea and explore it theoretically even before the experiments are done, and sometimes they come up with predictions that seem a little crazy at first. What is so exciting now is that we have data that shows these ideas are not so crazy," Crommie said. "The observation of these giant pseudomagnetic fields opens the door to room-temperature 'straintronics,' the idea of using mechanical deformations in graphene to engineer its behavior for different electronic device applications."

Crommie noted that the "pseudomagnetic fields" inside the nanobubbles are so high that the energy levels are separated by hundreds of millivolts, much higher than room temperature. Thus, thermal noise would not interfere with this effect in graphene even at room temperature. The nanobubble experiments performed in Crommie's laboratory, however, were performed at very low temperature.

Normally, electrons moving in a magnetic field circle around the field lines. Within the strained nanobubbles, the electrons move in circles in the plane of the graphene sheet, as if a strong magnetic field has been applied perpendicular to the sheet even when there is no actual
magnetic field. Apparently, Crommie said, the pseudomagnetic field only affects moving electrons and not other properties of the electron, such as spin, that are affected by real magnetic fields.

Other authors of the report, in addition to Crommie, Castro Neto and Guinea, are Sarah Burke, now a professor at the University of British Columbia; Niv Levy, now a postdoctoral researcher at the National Institute of Technology and Standards; and graduate student Kacey L. Meaker, undergraduate Melissa Panlasigui and physics professor Alex Zettl of UC Berkeley.

The research was funded through the U.S. Department of Energy Office of Science and the U.S. Office of Naval Research.

####

For more information, please click here

Contacts:
SOURCE:
Michael Crommie
(510) 642-9392


Robert Sanders
(510) 643-6998

Copyright © University of California, Berkeley

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 News Press

News and information

Carbon Sciences Developing Breakthrough Technology to Mass-Produce Graphene -- the New Miracle Material: Company Enters Into an Agreement With the University of California, Santa Barbara (UCSB) to Fund the Further Development of a New Graphene Process September 16th, 2014

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

Effective Nanotechnology Innovations to Receive Mustafa Prize September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Possible Futures

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Academic/Education

Malvern technology delivers Malvern reliability in multi-disciplinary lab at Queen Mary University London September 9th, 2014

State University of New York Trustees Unanimously Approve SUNY Polytechnic Institute (SUNY Poly) as New Name for Merged SUNY CNSE / SUNYIT September 9th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

Nanotubes/Buckyballs

‘Small’ transformation yields big changes September 16th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Berkeley Lab Licenses Boron Nitride Nanotube Technology: New material has unique mechanical and electronic properties September 13th, 2014

Global Energy Systems Signs Master Sales Agreement with China Aviation Supplies Group September 4th, 2014

Discoveries

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

Announcements

Carbon Sciences Developing Breakthrough Technology to Mass-Produce Graphene -- the New Miracle Material: Company Enters Into an Agreement With the University of California, Santa Barbara (UCSB) to Fund the Further Development of a New Graphene Process September 16th, 2014

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

Effective Nanotechnology Innovations to Receive Mustafa Prize September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Research partnerships

Carbon Sciences Developing Breakthrough Technology to Mass-Produce Graphene -- the New Miracle Material: Company Enters Into an Agreement With the University of California, Santa Barbara (UCSB) to Fund the Further Development of a New Graphene Process September 16th, 2014

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

NEI Corporation and PneumatiCoat Technologies Sign Agreement to Jointly Develop and Market New Materials for Lithium-ion Batteries September 12th, 2014

Researchers Create World’s Largest DNA Origami September 11th, 2014

Quantum nanoscience

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

Layered graphene sandwich for next generation electronics September 8th, 2014

Cool Calculations for Cold Atoms: New theory of universal three-body encounters September 2nd, 2014

New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE