Coexistence of superconductivity and superparamagnetism in Pb–Co electrodeposited nanowires

Pb–Co nanowires were electrodeposited in 100 nm nominal pore diameter polycarbonate membranes. Above the T of Pb we modelled the behaviour of the wires with a Langevin function, obtaining a Co volume of (1.06 ± 0.01) × 10 cm divided into clusters of ≈10 atoms in size. The magnetic response of the wires in the 3–10 K interval, which comprises T, was modelled by adding spherical superconducting Pb grains to the Co clusters; the Pb grains were found to be (87 ± 6) nm in diameter. The Co clusters were not interacting and were not magnetically screened by the superconducting Pb.