EXAFS STUDY OF THE LOCAL STRUCTURE IN AFe2As2 SYSTEMS (A=Sr, Eu, Ba)

D. TOBIA; M. E. SALETA; M. RADAELI; M. M. PIVA; S. J. A. FIGUEROA; G. G. LESSEUX; C. B. R. JESUS; R. R. URBANO; E. GRANADO; P. G. PAGLIUSO

San Luis

Congreso; XII Reunion Anual de la Asociación Argentina de Cristalografía; 2016

The recent discovery of intermetallic Fe-based superconductors has opened new fields for investigating the mechanisms responsible for the superconductivity in these high temperature superconductors. [1] From the structural point of view, these Fe-based materials share a local structure, based on planar layers of FeAs. The Fe 3d electrons form multiple bands at the Fermi level and play an important role in superconductivity. The non-doped AFe2As2 compounds, called A122, are oxygen free iron arsenides (with A= Ba, Sr, Ca, Eu). At room temperature they are paramagnetic and crystallize in a tetragonal structure. At low temperature they exhibit a spin-density-wave (SDW) ordering transition, connected with a structural phase transition to an orthorhombic structure. This phase is formed at a critical temperature TSDW, observed typically in the 100K