The influence of BaSnO3 artificial pinning centres on the resistive transition of 2G high-temperature superconductor wire in magnetic field

Abstract

In this work, we present a study of the resistive transition in magnetic field of 2G high-temperature superconductor wire samples with BaSnO3 (BSO) artificial pinning centres (APCs) in a GdBa2Cu3O7−x (GdBCO) superconductor. The GdBCO layer was fabricated by pulsed laser deposition, using production equipment to obtain samples with varied concentrations of APC: 0, 6, 12 and 18 mol% of BSO. Resistive transition curves were measured in the magnetic field range from 0 to 9 T, and magnetic field orientations from B∣∣c (θ = 0°) to B∣∣ab (θ = 90°) with an angle step of 15°. We observed an irreversibility temperature peak at the B∣∣ab orientation. We determined the angular regions where correlated pinning centres dominated and found them to expand with the increase of BSO concentration. The activation energy (Ua) obtained from the lg(ρ/ρ0) against the 1/T plots was almost constant in the whole angular range, with a small peak at B∣∣ab. The activation energy as well as the irreversibility temperature decreased with the increasing doping level, but the Ua(θ) curves looked similar for all samples with APCs. The logarithmic resistivity plot of the undoped sample looked substantially different from those of the APC samples, with a kink and two different slopes corresponding to two regions with different Ua. We discuss that this difference is related to the different pinning landscapes in samples with and without APCs.