Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > New instrument puts new spin on superconductors: Ames Lab researchers team up to probe iron-arsenic superconductors

Abstract:
Researchers at the U.S. Department of Energy's Ames Laboratory are part of collaborative team that's used a brand new instrument at the DOE's Spallation Neutron Source to probe iron-arsenic compounds, the "hottest" new find in the race to explain and develop superconducting materials. Rob McQueeney, an Ames Laboratory physicist, was part of that team whose findings, published in the Oct. 8 issue of Physical Review Letters, mark the first research produced with the aid of the new tool.

New instrument puts new spin on superconductors: Ames Lab researchers team up to probe iron-arsenic superconductors

AMES, IA | Posted on October 11th, 2008

The Spallation Neutron Source - SNS for short - is the DOE's sprawling new $1.4 billion complex operated by Oak Ridge National Laboratory in the rolling green hills of eastern Tennessee. The SNS uses a pulsed neutron beam to provide information about the structure and dynamics of materials that cannot be obtained from X-rays or electron microscopes. Although neutral in electrical charge, neutrons interact with the nucleus. The neutron's magnetic moment can also interact with magnetic spins in a material. As neutrons from the beam pass through a material, they scatter off the nuclei and spins. By measuring the speed and angle of the scattered neutrons, scientists are able to develop detailed information about the positions and the motion of the nuclei and spins within the material.

McQueeney serves on the Executive Committee of the Instrumentation Development Team for ARCS, a wide angular-range chopper spectrometer designed to measure the vibrations of atomic nuclei. The sixth of the proposed 24 instruments to be built at the SNS, ARCS is undergoing final testing and is available for general use this fall, but McQueeney is already impressed with the results.

"The preliminary results are amazing," McQueeney said. "I have experience with a similar instrument and ARCS blew it away," adding that it produces better results from smaller samples in a much shorter time frame.

The timing of the testing phase for ARCS was ideal because in the preceding months, a new class of superconducting materials - pnictide compounds based on iron and arsenic - was discovered. This allowed McQueeney and collaborators at Oak Ridge National Laboratory and California Institute of Technology to look specifically at lanthanum-iron-arsenide (LaFeAsO0.89F0.11). One of the samples studied was produced by McQueeney's Ames Laboratory colleague, physicist and crystal-growth expert Paul Canfield. When this new class of superconductors was first announced, Canfield was able to quickly replicate the results and develop additional compounds.

The phenomenon of superconductivity is caused by the pairing of conduction electrons due to forces within the crystal. The origin of this pairing is one of the great unsolved mysteries in the field of high-temperature superconductivity.

"There are two prevailing ideas behind superconductivity," McQueeney said. "One is that pairing is mediated by lattice vibrations. The other is that it's mediated by magnetic or spin fluctuations."
Since neutrons are capable of measuring both the lattice vibrations and spin fluctuations, they are an ideal probe to gain an understanding of superconductivity.

The experiments focused on understanding the role of lattice vibrations in the new superconductors. The vibration of atoms within the crystal lattice creates a pattern of waves called phonons. When a neutron collides with this lattice, it can give up some of its energy to create a phonon. The difference in the neutron's energy before and after the collision is equal to the phonon energy.

"Our measurements did not support the conventional electron-phonon mediated superconductivity," McQueeney said, adding that theoretical calculations matched up fairly well with measurements obtained with ARCS. While the results are an important first step, there is still much work to be done to determine the origin of superconductivity in the iron-arsenides. McQueeney and his collaborators are continuing studies of phonons and spin excitations in these compounds.

The quest to understand and develop superconductor technology has important energy implications. By their nature, and as the name implies, superconductors can conduct electrical current with virtually no power loss, unlike conventional electric transmission lines which lose up to 30% due to resistance in the system. Basic research to understand the atomic interactions that make superconductors work, and to potentially control those properties, is one way that Ames Laboratory strives to address the scientific challenges facing our country.

####

About Ames Laboratory
Ames Laboratory is a U.S. Department of Energy Office of Science research facility operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solution. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global challenges.

For more information, please click here

Contacts:
Robert McQueeney
Division of Materials Science and Engineering
515-294-3545


Kerry Gibson
Public Affairs
515-294-1405

Copyright © Ames Laboratory

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

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

So, near and yet so far: Stable HGNs for Raman April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Laboratories

Rutgers, NIST physicists report technology with potential for sub-micron optical switches March 31st, 2015

Using magnetic fields to understand high-temperature superconductivity: Los Alamos explores experimental path to potential 'next theory of superconductivity' March 27th, 2015

ORNL-led team demonstrates desalination with nanoporous graphene membrane March 25th, 2015

Los Alamos Offers New Insights Into Radiation Damage Evolution: TUnderstanding defects in materials aids in performance predictions March 18th, 2015

Discoveries

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Light-powered gyroscope is world's smallest: Promises a powerful spin on navigation April 1st, 2015

Announcements

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

So, near and yet so far: Stable HGNs for Raman April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Tools

So, near and yet so far: Stable HGNs for Raman April 1st, 2015

PIHera: Largest Family of Piezo Stage Scanners with 10X Greater Positioning Area March 31st, 2015

New Applications Brochure on Complex Motion Control Systems for Scientific Research March 31st, 2015

'Atomic chicken-wire' is key to faster DNA sequencing March 30th, 2015

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 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE