We have studied the effect of chemical pressure on the local structure of La1-xSmxFeAsO oxypnictides. The combination of arsenic K-edge and rare-earth (RE = La, Sm) L-3-edge x-ray absorption spectra has permitted us to determine local bondlengths and unoccupied electronic states with varying chemical pressure controlled by the size difference of La and Sm. The Fe-As distance is hardly affected by the chemical pressure, and remains covalent as shown by As Kedge extended x-ray absorption fine structure (EXAFS) analysis. On the other hand, the As-RE and As-As distances show a gradual change. The changes indicate a larger effect of chemical pressure in the REO spacer layer and on the interlayer interactions, consistent with x-ray absorption near edge structure (XANES) data. The results suggest that interlayer atomic correlations are likely to have an important role in the physical properties of the La1-xSmxFeAsO parent phases of the superconducting oxypnictides.
Effect of chemical pressure on the local structure of La1−xSmxFeAsO system / Iadecola, Antonella; Joseph, B.; Paris, E.; Provino, A.; Martinelli, A.; Manfrinetti, P.; Putti, M.; Saini, Naurang Lal. - In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY. - ISSN 0953-2048. - STAMPA. - 28:2(2015), p. 025007. [10.1088/0953-2048/28/2/025007]
Effect of chemical pressure on the local structure of La1−xSmxFeAsO system
IADECOLA, ANTONELLA;E. Paris;SAINI, Naurang Lal
2015
Abstract
We have studied the effect of chemical pressure on the local structure of La1-xSmxFeAsO oxypnictides. The combination of arsenic K-edge and rare-earth (RE = La, Sm) L-3-edge x-ray absorption spectra has permitted us to determine local bondlengths and unoccupied electronic states with varying chemical pressure controlled by the size difference of La and Sm. The Fe-As distance is hardly affected by the chemical pressure, and remains covalent as shown by As Kedge extended x-ray absorption fine structure (EXAFS) analysis. On the other hand, the As-RE and As-As distances show a gradual change. The changes indicate a larger effect of chemical pressure in the REO spacer layer and on the interlayer interactions, consistent with x-ray absorption near edge structure (XANES) data. The results suggest that interlayer atomic correlations are likely to have an important role in the physical properties of the La1-xSmxFeAsO parent phases of the superconducting oxypnictides.File | Dimensione | Formato | |
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