Neutron irradiation of SmFeAsO 1x F x

SmFeAsO1−x Fx was irradiated in a fission reactor by a fast (E > 0.1 MeV) neutron fluence of 4 × 10 21 m −2 . The introduced defects increased the normal state resistivity due to a reduction in the mean free path of the charge carriers. This leads to an enhancement of the upper critical field at low temperatures. The critical current density within the grains, Jc, increases upon irradiation. The second maximum in the field dependence of Jc disappears and the critical current density becomes a monotonically decreasing function of the applied magnetic field. (Some figures in this article are in colour only in the electronic version)