Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Magnetism flicks switch on "dark excitons"

Abstract:
Tests At Leading Magnetic Labs Shed Light On Nanotube Mystery

Magnetic Transistor Could "Dial In" Quantum Effects

Houston, TX | Posted on January 10, 2006

In new experimental research appearing in this week's issue of Physical Review Letters, a Rice University-led team of nanoscientists and electrical engineers has flipped the switch on "dark excitons" in carbon nanotubes by placing them inside a strong magnetic field.

The research offers new insight into the fundamental optical properties of semiconducting nanotubes, hollow straw-like molecules of pure carbon. Leading computing companies would like to use nanotubes as optical components in next-generation microchips that are faster, more powerful and more energy efficient.

"Single-walled carbon nanotubes offer engineers the intriguing possibility of building chips where electrical inputs can be converted into light and moved about the chip as optical signals rather than electrical signals," said lead researcher Junichiro Kono, associate professor of electrical and computer engineering at Rice. "Thus far, the poor optical performance of nanotubes - in some cases as few as one in 100,000 incoming photons causes a fluorescent emission - has prevented engineers from developing the technology for applications."

Kono said the new research may help scientists formulate new tests to answer some of the most perplexing questions about the optical properties of nanotubes. For example, scientists are currently debating whether low fluorescence efficiencies in nanotubes arise from the intrinsic physical structure of nanotubes or from external factors like structural defects and impurities. Some of the leading theories have the missing light disappearing into "dark" excitons - odd quantum pairings of electrons and electron "holes" that are forbidden by quantum rules from fluorescing. The new magnetic method of overcoming this dark exciton effect could be used to probe the intrinsic properties of nanotubes and help settle the debate.

The team tested materials in some of the world's most powerful magnetic fields. Experiments were conducted at both the Laboratoire National des Champs Magnétiques Pulsés in Toulouse, France, and at the National High Magnetic Field Laboratory at New Mexico's Los Alamos National Laboratory.

"We hope that our experimental methods will help better inform theorists and ultimately aid in the development of new devices with far superior functions than those based on existing technology," said Sasa Zaric, whose doctoral dissertation will be based on the work.

Nanotubes are a fraction of the size of transistors used in today's best microchips. As electronic components, nanotubes could reduce power demands and heating in next-generation chips. But as optical components they offer far more. The replacement of copper cables with fiberoptics revolutionized the volume and speed of data transmission in the telecom industry 20 years ago, and the parallels in microchips are tantalizing.

The research was funded by the Robert A. Welch Foundation and the National Science Foundation. Rice co-authors include electrical and computer engineering's Sasa Zaric, Gordana Ostojic and Jonah Shaver, and chemistry's Valerie Moore, Robert Hauge and Richard Smalley. Other co-authors include Oliver Portugall, Paul Frings and Geert Rikken, all of the Laboratoire National des Champs Magnétiques Pulsés in Toulouse, France; Madalina Furis and Scott Crooker of the National High Magnetic Field Laboratory at Los Alamos National Laboratory; and Xing Wei of the National High Magnetic Field Laboratory at Florida State University.

####

About Rice University:
Rice University is consistently ranked one of America's best teaching and research universities. It is distinguished by its: size: 2,850 undergraduates and 1,950 graduate students; selectivity: 10 applicants for each place in the freshman class; resources: an undergraduate student-to-faculty ratio of 6-to-1, and the fifth largest endowment per student among American universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work. Rice's wooded campus is located in the nation's fourth largest city and on America's South Coast.



For more information, please click here

Contact:
Jade Boyd
(713) 348-6778
jadeboyd@rice.edu

Copyright © Rice University

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

Possible Futures

Tuning into quantum: Scientists unlock signal frequency control of precision atom qubits July 16th, 2018

Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication July 13th, 2018

UMBC researchers develop nanoparticles to reduce internal bleeding caused by blast trauma July 13th, 2018

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides July 13th, 2018

Nanotubes/Buckyballs/Fullerenes/Nanorods

Carbon is the new black: Researchers use carbon nanotubes to develop clothing that can double as batteries July 10th, 2018

Nano-saturn: Supramolecular complex formation: Anthracene macrocycle and C60 fullerene June 8th, 2018

Unzipping graphene nanotubes into nanoribbons: New study shows elegant mathematical solution to understand how the flow of electrons changes when carbon nanotubes turn into zigzag nanoribbons June 6th, 2018

Making carbon nanotubes as usable as common plastics: Researchers discover that cresols disperse carbon nanotubes at unprecedentedly high concentrations May 15th, 2018

Nanoelectronics

GLOBALFOUNDRIES Surpasses $2 Billion in Design Win Revenue on 22FDX® Technology : With 50 client designs and growing, 22FDX proves its value as a cost-effective solution for power-sensitive applications July 9th, 2018

High-power electronics keep their cool with new heat-conducting crystals July 6th, 2018

Leti Presenting Strategic Vision and Hosting a Workshop at SEMICON West: “From Electrons to Photons” Leti Workshop and CEO Media Briefing Set for Tuesday, July 10 in W Hotel, San Francisco June 12th, 2018

Quantum Interference May Be Key to Smaller Insulators: Breakthrough could jumpstart further miniaturization of transistors June 6th, 2018

Announcements

Tuning into quantum: Scientists unlock signal frequency control of precision atom qubits July 16th, 2018

Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication July 13th, 2018

UMBC researchers develop nanoparticles to reduce internal bleeding caused by blast trauma July 13th, 2018

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides July 13th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project