Disorder-induced changes of superconducting Tc obtained by low-temperature ion irradiation of simple metals and alloys

Abstract

By applying low-temperature (T<10 K) ion irradiation to continuously increase the disorder of Zn, Al, α-Ga, β-Ga, In, Pb, AuIn2, and Al2Au films, the corresponding relative changes of the superconducting transition temperature δt=ΔTc/Tc0 was studied as a function of the electrical resistivity ρ. In all cases, a linear δt-vs-ρ relation is observed over a wide range of resistivities. The corresponding slopes (δt/ρ) are compared to existing theories and good agreement is found, provided that experimental input parameters are used for the calculations. For Al, by ion-bombarding oxygen-containing films, the influence of these impurities on the value of (δt/ρ) could be demonstrated. In addition, by repeating vapor-quenching experiments onto liquid-helium-cooled substrates for Zn, α-Ga, and Al, earlier discrepancies concerning the value of (δt/ρ) are resolved. Even in cases in which an amorphous phase results by ion irradiation (α-Ga, AuIn2, Al2Au), a continuous δt-vs-ρ curve is obtained, emphasizing a universal behavior of Tc on disorder. But a detailed comparison of disorder produced by different preparation techniques clearly reveals deviations from such universality. This indicates that different types of defects act differently on Tc.

Source-reported materials — not catalogue approval

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