Determination of the local structure in FeSe0.25Te0.75 single crystal by polarized EXAFS
Dipartimento di Fisica, Università di Roma “La Sapienza” - P.le Aldo Moro 2, 00185 Roma, Italy, EU
2 European Synchrotron Radiation Facility - 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9, France, EU
3 National Institute for Materials Science - 1-2-1 Sengen, Tsukuba 305-0047, Japan
4 JST-TRIP - 1-2-1 Sengen, Tsukuba 305-0047, Japan
Accepted: 15 June 2010
Temperature-dependent polarized extended X-ray absorption fine-structure (EXAFS) measurements are made on the superconducting FeSe0.25Te0.75 single crystal. The Fe-Se bond length is found to be significantly shorter than the average crystallographic Fe-Se/Te distance, and almost equal to the one for the system without Te. On the other hand, the Fe-Te bond length is nearly equal to the one known for a binary FeTe system. This suggests that the Se and Te occupy distinct sites in the ternary FeSe0.25Te0.75, indicating the breaking of the average crystal symmetry with locally inhomogeneous atomic distribution.
PACS: 74.70.Xa – Pnictides and chalcogenides / 74.81.-g – Inhomogeneous superconductors and superconducting systems, including electronic inhomageneities / 61.05.cj – X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
© EPLA, 2010