Volume 87, Number 2, July 2009
|Number of page(s)||5|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||05 August 2009|
Local structure of ReFeAsO (Re = La, Pr, Nd, Sm) oxypnictides studied by Fe K-edge EXAFS
Dipartimento di Fisica, Università di Roma “La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy, EU
2 Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN - Boulevard du Marechal Juin, 14050 Caen, France, EU
3 Department of Physics and Astronomy, Vrije Universiteit - De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands, EU
4 European Synchrotron Radiation Facility - 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9, France, EU
5 Department of Materials Science and Engineering, State University of New York at Stony Brook Stony Brook, NY 11794, USA
6 Brookhaven National Laboratory - Upton, NY 11973, USA
Corresponding author: email@example.com
Accepted: 9 July 2009
Local structure of ReOFeAs (Re = La, Pr, Nd, Sm) system has been studied as a function of chemical pressure varied due to different rare-earth size. Fe K-edge extended X-ray absorption fine structure (EXAFS) measurements in the fluorescence mode has permitted to compare systematically the inter-atomic distances and their mean square relative displacements (MSRD). We find that the Fe-As bond length and the corresponding MSRD hardly show any change, suggesting the strongly covalent nature of this bond, while the Fe-Fe and Fe-Re bond lengths decrease with decreasing rare-earth size. The results provide important information on the atomic correlations that could have direct implication on the superconductivity and magnetism of ReOFeAs system, with the chemical pressure being a key ingredient.
PACS: 61.05.cj – X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc. / 74.62.Bf – Effects of material synthesis, crystal structure, and chemical composition / 74.81.-g – Inhomogeneous superconductors and superconducting systems
© EPLA, 2009
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