Superconductivity and structural disorder in ion-irradiated rhenium films

Abstract

Single- and polycrystalline Re films were irradiated at room temperature and liquid nitrogen temperature with 350-keV N ions and 700-keV doubly charged Ar ions. With increasing ion fluence ф, the ion-induced residual resistivity Δρ0 and the superconducting transition temperatureT c were observed to increase. The functional behavior of Δρ0(ф) and the recovery spectra are found to depend on ion species and ф. Annealing stages II and III are seen after low-dose N- and Ne-ion irradiation, whereas at high ion fluences stages II, IV, and V are most pronounced. Thus the increase of ρ0 at low fluences is attributed to vacancies mainly, and at high fluences to the formation of extended defects. TheT c increase at low fluences is caused by inhomogeneously distributed vacancies, and at high fluences by vacancies pinned to dislocations. Extended defects alone do not seem to have any influence onT c . Ion-induced recrystallization processes have also been observed.