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SCI-BYTES - WHAT'S NEW IN RESEARCH : 2009

Week of November 15, 2009 < Back ¦ 2009 ¦ Home

Hot Paper in Hot Paper in Chemistry

"Magnetic order close to superconductivity in the iron-based layered La0(1-x)F(x)FeAs systems," by Clarina de la Cruz and 10 others, Nature, 7197(453): 899-902, 12 June 2008.

[Authors' affiliations: University of Tennessee, Knoxville; Oak Ridge National Lab, TN; NIST, Gaithersburg, MD; University of Maryland, College Park; Ames Lab and Iowa State University; Beijing National Laboratory for Condensed Matter Physics, China]

Abstract: "Following the discovery of long-range antiferromagnetic order in the parent compounds of high-transition-temperature (high-Tc) copper oxides, there have been efforts to understand the role of magnetism in the superconductivity that occurs when mobile 'electrons' or 'holes' are doped into the antiferromagnetic parent compounds. Superconductivity in the newly discovered rare-earth iron-based oxide systems ROFeAs (R, rare-earth metal) also arises from either electron or hole doping of their non-superconducting parent compounds. The parent material LaOFeAs is metallic but shows anomalies near 150 K in both resistivity and d.c. magnetic susceptibility. Although optical conductivity and theoretical calculations suggest that LaOFeAs exhibits a spin-density-wave (SDW) instability that is suppressed by doping with electrons to induce superconductivity, there has been no direct evidence of SDW order. Here we report neutron-scattering experiments that demonstrate that LaOFeAs undergoes an abrupt structural distortion below 155 K, changing the symmetry from tetragonal (space group P4/nmm) to monoclinic (space group P112/n) at low temperatures, and then, at ~137 K, develops long-range SDW-type antiferromagnetic order with a small moment but simple magnetic structure. Doping the system with fluorine suppresses both the magnetic order and the structural distortion in favour of superconductivity. Therefore, like high-Tc copper oxides, the superconducting regime in these iron-based materials occurs in close proximity to a long-range-ordered antiferromagnetic ground state."

This 2008 report from Nature was cited 54 times in current journal articles indexed by Clarivate Analytics during July-August 2009. For what is now the sixth bimonthly period in a row, this paper scores at #2 among non-review entries in the Hot Papers "chemistry" category (although, as has been noted previously, this multidisciplinary report is also recording numerous citations in physics journals). Prior to the most recent two-month count, citations to the paper have accrued as follows:

May-June 2009: 47 citations
March-April 2009: 69
January-February 2009: 52
November-December 2008: 62
September-October 2008: 34
July-August 2008: 15
Total citations to date: 333


SOURCE: Hot Papers Database (Included with a subscription to the print newsletter Science Watch®, available from the Research Services Group of Thomson Reuters. Packaged on a CD that is mailed with each Science Watch issue, the Hot Papers Database contains data on hundreds of highly cited papers published during the last two years. User interface permits searching by author, organization, journal, field, and more. Total citations, as well as citations accrued during successive bimonthly periods, can be assessed and graphed. An updated CD containing the most recent bimonthly data is mailed with every new issue of Science Watch, six times a year. The CD also includes an electronic version of the Science Watch issue in HTML format, for personal desktop access.

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