  In this work we present a systematic experimental and theoretical study of
the structural, transport and superconducting properties of
Sm(Fe1-xRux)As(O0.85F0.15) polycrystalline samples as a function of Ru content
(x) ranging from 0 to 1. The choice of Ru as isoelectronic substitution at Fe
site of F-doped compounds allows to better clarify the role of structural
disorder in modifying the normal and superconducting properties of these newly
discovered multiband superconductors. Two different regions are identified: the
Fe-rich phase (x<0.5) where superconducting and normal state properties are
strongly affected by disorder induced by Ru substitution; the Ru-rich phase
(x>0.5) where the system is metallic and strongly compensated and the presence
of Ru frustrates the magnetic moment on Fe ions. Here the lack of magnetic
features and related spin fluctuations may be the cause for the suppression of
superconductivity.
