title: Temperature-dependent local structure of NdFeAsO(1-x)F(x) system using arsenic K-edge extended x-ray absorption fine structure.
abstract: Local structure of NdFeAsO(1-x)F(x) (x = 0.0, 0.05, 0.15 and 0.18) high temperature iron-pnictide superconductor system is studied using arsenic K-edge extended x-ray absorption fine structure measurements as a function of temperature. Fe-As bond length shows only a weak temperature and F-substitution dependence, consistent with the strong covalent nature of this bond. The temperature dependence of the mean square relative displacements of the Fe-As bond length are well described by the correlated Einstein model for all the samples, but with different Einstein temperatures for the superconducting and non-superconducting samples. The results indicate distinct local Fe-As lattice dynamics in the superconducting and non-superconducting iron-pnictide systems.
authors.affiliation: Dipartimento di Chimica, Sezione di Chimica Fisica, INSTM (UdR Pavia), Università di Pavia, Viale Taramelli 16, 27100 Pavia, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Joseph
authors.forename: A
authors.initials: A
authors.lastname: Iadecola
authors.forename: L
authors.initials: L
authors.lastname: Malavasi
authors.forename: N L
authors.initials: NL
authors.lastname: Saini