The nanoscale structure and unoccupied valence electronic states in FeSe1-xTex chalcogenides probed by X-ray absorption measurements

• Published in: Physical chemistry chemical physics : PCCP Vol. 17; no. 27; pp. 18131 - 18137
• Main Authors: Hacisalihoglu, M Y, Paris, E, Joseph, B, Yanmaz, E, Saini, N L
• Format: Journal Article
• Language: English
• Published: England 21.07.2015
• ISSN: 1463-9084
• DOI: 10.1039/c5cp01740h

We have studied the nanoscale structure and unoccupied electronic states in FeSe1-xTex by a combined analysis of Se K, Te L1 and Fe K-edges X-ray absorption measurements. Extended X-ray absorption fine structure (EXAFS) results show that iron-chalcogen (Fe-Se and Fe-Te) distances in ternary FeSe1-xTex are similar to those measured for binary FeSe and FeTe. The local Fe-Se/Te distances determined by different absorption edges fit well in the characteristic Z-plot of random alloys, providing unambiguous support to the inhomogeneous nanoscale structure of the ternary FeSe1-xTex system. X-ray absorption near-edge structure (XANES) spectra reveal a gradual evolution of the unoccupied valence electronic states as a function of Te-substitution in FeSe1-xTex. The Fe 3d-Se 4p/Te 5p hybridization is found to decrease with Te-substitution, accompanied by an increase in unoccupied Se 4p states and a decrease in unoccupied Te 5p states. The results are discussed in the frame of local inhomogeneity in the FeSe1-xTex system driven by random alloying of Se/Te atoms.