Featured Research

from universities, journals, and other organizations

New Instrument Puts New Spin On Superconductors

Date:
October 16, 2008
Source:
DOE/Ames Laboratory
Summary:
The race to understand the latest superconducting iron-arsenic compounds has taken another step forward. Researchers have used a brand new instrument that indicates the compound's superconducting properties could be related to magnetic spins rather than lattice vibrations.

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.

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.


Story Source:

The above story is based on materials provided by DOE/Ames Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

DOE/Ames Laboratory. "New Instrument Puts New Spin On Superconductors." ScienceDaily. ScienceDaily, 16 October 2008. <www.sciencedaily.com/releases/2008/10/081010172447.htm>.
DOE/Ames Laboratory. (2008, October 16). New Instrument Puts New Spin On Superconductors. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2008/10/081010172447.htm
DOE/Ames Laboratory. "New Instrument Puts New Spin On Superconductors." ScienceDaily. www.sciencedaily.com/releases/2008/10/081010172447.htm (accessed October 22, 2014).

Share This



More Matter & Energy News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) — Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) — Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) — As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com
What Is Magic Leap, And Why Is It Worth $500M?

What Is Magic Leap, And Why Is It Worth $500M?

Newsy (Oct. 22, 2014) — Magic Leap isn't publicizing much more than a description of its product, but it’s been enough for Google and others to invest more than $500M. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins