LAUSR

Magnetic impurities in metallic superconductors are important for both fundamental and applied sciences. In this study, we focused on dilute Mn-doped aluminum (AlMn) films, which are common superconducting materials used to make transition edge sensors and other superconducting devices. We developed a multi-energy ion-implantation technique to make AlMn films. Compared with frequently used sputtering techniques, ion-implantation provides more precise control of the Mn doping concentration in the AlMn films. It enables us to fabricate reliably AlMn films with a different superconducting transition temperature ( T c ) that can match a variety of application needs. We also found that the superconducting transition temperature drops with increasing film thickness for samples with the same nominal concentration of Mn dopants. The dependence of T c on the film thickness is attributed to the increasing implantation energy. By quantitatively analyzing the curves of T c versus the Mn doping concentration, we propose that Mn dopants act as magnetic impurities and suppression of superconductivity is counteracted by the antiferromagnetic Ruderman–Kittel–Kasuya–Yosida interaction among Mn dopants, which is influenced by the defects induced in the ion-implantation process.