Scientists probing iron-arsenic compounds to create superconductors

October 11th, 2008 - 11:54 am ICT by ANI  

Washington, October 11 (ANI): American researchers are using a brand new instrument to probe iron-arsenic compounds, with a view to better understanding and developing superconductors.
The collaborative team behind the project includes experts from the U.S. Department of Energys Ames Laboratory.
The instrument they are using for their research is situated at the DOEs sprawling new 1.4 billion-dollar complex, the Spallation Neutron Source (SNS), which is 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, which cannot be obtained from X-rays or electron microscopes.
Neutrons, though neutral in electrical charge, interact with the nucleus. Their magnetic moment can also interact with magnetic spins in a material.
When neutrons from the beam pass through a material, they scatter off the nuclei and spins. Measuring the speed and angle of the scattered neutrons can help develop detailed information about the positions and the motion of the nuclei and spins within the material.
McQueeney, who served on the Executive Committee of the Instrumentation Development Team, has revealed that their tool is the sixth of the proposed 24 instruments to be built at the SNS.
He describes the instrument called ARCS as a wide angular-range chopper spectrometer designed to measure the vibrations of atomic nuclei.
He says that ARCS, though undergoing final testing, has already provided impressive results.
The preliminary results are amazing. I have experience with a similar instrument and ARCS blew it away, McQueeney said, adding that it produces better results from smaller samples in a much shorter time frame.
The phenomenon of superconductivity is caused by the pairing of conduction electrons due to forces within the crystal, a phenomenon whose origin is one of the great unsolved mysteries in the field of high-temperature superconductivity.
There are two prevailing ideas behind superconductivity. One is that pairing is mediated by lattice vibrations. The other is that its mediated by magnetic or spin fluctuations, McQueeney said.
He said that the capability of neutrons to measure both the lattice vibrations and spin fluctuations makes them an ideal instrument for researching and understanding superconductivity.
The quest to understand and develop superconductor technology has important energy implications, as superconductors can conduct electrical current with virtually no power loss, unlike conventional electric transmission lines that lose up to 30 per cent due to resistance in the system.
The researchers say that basic research to understand the atomic interactions that make superconductors work, and to potentially control such properties, may be helpful in addressing many scientific challenges.
An article on the research project has been published in the journal Physical Review Letters (ANI)

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