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


Hacisalihoglu M. Y. , Paris E., Joseph B., Yanmaz E. , Saini N. L.

PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol.17, no.27, pp.18131-18137, 2015 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 17 Issue: 27
  • Publication Date: 2015
  • Doi Number: 10.1039/c5cp01740h
  • Title of Journal : PHYSICAL CHEMISTRY CHEMICAL PHYSICS
  • Page Numbers: pp.18131-18137

Abstract

We have studied the nanoscale structure and unoccupied electronic states in FeSe1-xTex by a combined analysis of Se K, Te L-1 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.