Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
by Staff Writers
Oak Ridge TN (SPX) May 07, 2014
For the first time, scientists have a clearer understanding of how to control the appearance of a superconducting phase in a material, adding crucial fundamental knowledge and perhaps setting the stage for advances in the field of superconductivity.
The paper, published in Physical Review Letters, focuses on a calcium-iron-arsenide single crystal, which has structural, thermodynamic and transport properties that can be varied through carefully controlled synthesis, similar to the application of pressure.
To make this discovery, researchers focused on how these changes alter the material's Fermi surface, which maps the specific population and arrangement of electrons in materials.
"The Fermi surface is basically the 'genetic code' for causing a certain property, including superconductivity, in a material," said Athena Safa-Sefat of the Department of Energy's Oak Ridge National Laboratory, which led the research team.
"We can make different phases of this material in single crystal forms and measure their structure and properties, but now we have Fermi surface signatures that explain why we can't induce superconductivity in a certain structural phase of this material."
Superconducting wires conduct electricity without resistance and could save the nation billions of dollars per year by virtually eliminating transmission losses on the grid, or they can be used to make compact, light and powerful motors and generators.
This particular material is of special interest because it adds critical knowledge to the field of superconductivity that will ultimately allow such widespread applications.
The lead author of this paper, Krzysztof Gofryk, who did this work as a post-doctoral fellow at ORNL, showed how the interplay of structure and magnetism affected the Fermi surface and hence the electronic properties.
In calcium-iron-arsenide, the bulk superconducting state is absent because of the large Fermi surface modification at the structural transition.
This work represents a significant step forward for understanding this material's rich phase diagram and causes of superconductivity, Sefat said.
Other authors of the paper, titled "Fermi-Surface Reconstruction and Complex Phase Equilibria in CaFe2As2," are ORNL's post-doctoral fellow Bayrammurad Saparov and scientists from Los Alamos National Laboratory and Dresden University of Technology. The paper is available here
Oak Ridge National Laboratory
Space Technology News - Applications and Research
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|