  We report measurements of resistivity, magnetoresistivity, Hall effect,
Seebeck coefficient, infrared reflectivity of undoped SmFeAsO and lightly doped
SmFeAs(O0.93F0.07) oxypnictides. All the properties measured on SmFeAsO are
characterized by clear signatures of the magnetic instability. A
self-consistent picture emerges in which below the magnetic transition carrier
condensation occurs due to the opening of spin density wave (SDW) gap. This is
accompanied by the mobility increase of not gapped carriers due to the
suppression of electron-electron scattering. SmFeAs(O0.93F0.07) exhibits an
increase of the metallic character on cooling consistent with electron doping,
even though at room temperature values of all the properties nearly overlaps
with those of SmFeAsO. However, with temperature decrease all anomalies related
to the SDW instability are missed and the superconducting transition occurs.
This suggests that doping breaks abruptly the symmetries of the Fermi surface
inhibiting the SDW formation in favor of the superconducting transition, with
no substantial changes in the density of states or in the effective mass.
