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Hot Paper in Chemistry

"Superconductivity at 43 K in an iron-based layered compound LaO1-xFxFeAs," by Hiroki Takahashi and 5 others, Nature, 453(7193): 376-8, 15 May 2008. See also.

[Authors' affiliations: Nihon University, Tokyo, Japan; Tokyo Institute of Technology, Japan]

Abstract: "The iron- and nickel-based layered compounds LaOFeP and LaONiP have recently been reported to exhibit low-temperature superconducting phases with transition temperatures Tc of 3 and 5 K, respectively. Furthermore, a large increase in the midpoint Tc of up to similar to 26 K has been realized in the isocrystalline compound LaOFeAs on doping of fluoride ions at the O2- sites (LaO1-xFxFeAs). Experimental observations and theoretical studies suggest that these transitions are related to a magnetic instability, as is the case for most superconductors based on transition metals. In the copper-based high-temperature superconductors, as well as in LaOFeAs, an increase in Tc is often observed as a result of carrier doping in the two-dimensional electronic structure through ion substitution in the surrounding insulating layers, suggesting that the application of external pressure should further increase T-c by enhancing charge transfer between the insulating and conducting layers. The effects of pressure on these iron oxypnictide superconductors may be more prominent than those in the copper-based systems, because the As ion has a greater electronic polarizability, owing to the covalency of the Fe-As chemical bond, and, thus, is more compressible than the divalent O2- ion. Here we report that increasing the pressure causes a steep increase in the onset Tc of F-doped LaOFeAs, to a maximum of similar to 43 K at similar to 4 GPa. With the exception of the copper-based high-Tc superconductors, this is the highest Tc reported to date. The present result, together with the great freedom available in selecting the constituents of isocrystalline materials with the general formula LnOTMPn (Ln, Y or rare-earth metal; TM, transition metal; Pn, group-V, 'pnicogen', element), indicates that the layered iron oxypnictides are promising as a new material platform for further exploration of high-temperature superconductivity."

This 2008 report from Nature on an iron-based superconductor was cited 39 times in current journal articles indexed by Clarivate Analytics during March-April 2009. For the fourth consecutive bimonthly period, this paper registers as the #3 most-cited of any non-review paper published in the last two years and coded as chemistry (although by now the paper has also logged numerous citations recorded in physics journals). In fact, for the duration of this paper's run at #3, the first- and second-most-cited chemistry papers have also centered on iron-based superconductivity, with those slots consecutively occupied by the same two reports. Prior to the most recent bimonthly count, citations to the Takahashi et al. paper have accrued as follows:

January-February 2008: 37 citations
November-December 2008: 39
September-October 2008: 30
July-August 2008: 15
May-June 2008: 2

Total citations to date: 162

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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