Role of self-irradiation defects on the ageing of ²³⁹PuCoGa ₅

Low-temperature accumulation and annealing experiments, in conjunction with electrical resitivity and critical current density measurements, were used to study the ageing of the actinide superconductor PuCoGa₅. These measurements reveal that 2-nm-sized non-superconducting point-like regions are the main damages formed during room temperature ageing; smaller point-like defects are irrelevant to transport properties. Defect sizes and densities deduced from experiment agree with Transmission Electron Microscopy observations.