Development and characterization of Nb₃Sn superconductor wire with nanometric-scale pinning centers

The optimization of flux line pinning in superconductors is one of the most efficient ways to improve the transport properties of these materials. The generation of pinning centers in a controlled way and with a projected distribution can contribute to the estimation of the pinning acting on the flux lines and to the improvement of the critical current densities J_c. The present work shows the development and characterization of a Nb₃Sn superconducting wire with nanometric-scale Cu(Sn) artificial pinning centers (APC) introduced in a controlled manner into the superconducting phase. These nanometric APC regions change the properties of the superconducting phase, mainly due to the proximity effect and to the inelastic scattering of the electrons on the interfaces. The final wire, with 1.064.514 Nb filaments, was heat treated to form the Nb₃Sn phase and the Cu(Sn) APC regions at different external diameters, enabling the determination of the flux pinning behavior with the variation of the APC dimensions, in comparison to the superconducting coherence length. The results were analyzed under the microscopic point of view determining the influence of the APC presence on the superconducting properties.