Influence of radiation-induced disordering on the superconducting transition temperature of Nb3Ir films

Abstract

Evaporated single-phase A15 Nb3Ir films were irradiated at room temperature with protons and helium ions to study the influence of the induced defect structures determined by x-ray diffraction measurements on the superconducting transition temperature Tc. A reduction in Tc from 2.1 to 1.8 K was observed for energies deposited into nuclear collisions below 1 eV/atom. Beyond this threshold Tc increased and revealed values above the initial transition temperature of the unirradiated films depending on the irradiation conditions: 2.8 K for proton and 3.7 K for helium-ion irradiation. The changes in Tc were accompanied by a decrease of the Bragg-Williams long-range order parameter, a defect structure consisting of static displacements of the lattice atoms with average rms amplitudes in the range of 0.005 to 0.009 nm, and by partial amorphization. The maximum Tc value of 5.7 K was determined in totally amorphized films. Both the depressions and enhancements in Tc can be explained by changes of the electronic density of states at the Fermi energy due to smearing effects.

Source-reported materials — not catalogue approval

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