Critical current density in high-field superconductors described using wave-particle duality [dataset]

We report extensive measurements of the critical current density Jc as a function of magnetic field B, field angle θ, temperature T, and applied strain ε_{app} for a (RE)BCO coated conductor with artificial pinning centres (APCs), together with the effective upper critical field B_{c2}^{*ρ}(θ,T,ε_{app}) measured resistively down to ∼60 K. We show that the Jc data are not properly described using the standard scaling analysis for the volumetric pinning force using Fp ∝ F_{p,max}(b^p)(1− b)^q because it leads to non-physical values (∼1000 T) of the B_{c2}^{*ρ} at low temperatures. Here the Jc data are parameterised using an in-field superconducting-normal-superconducting Josephson-junction (J-J) model which includes the wave-particle nature of the superelectrons. The J-J model describes the power law behaviour of Jc at intermediate fields with free-parameter values describing very thin barriers—consistent with the APC (RE)BCO’s strongly textured microstructure and insulating inclusions and pins. We also show fits to Jc data for a (RE)BCO tape without APCs, and an ITER bronze route Nb_3Sn strand. For Nb_3Sn, the model describes the well-known Kramer-like high-field dependence of Jc, with free-parameter values that are consistent with the microstructure of optimised polycrystalline Nb_3Sn with ∼2 nm thick barriers that are ∼450 nm wide, strong triple-point pinning and distorted fluxons shuffling along the grain boundaries. Although more complex, the J-J analysis offers a better approach for optimising Jc than the standard scaling analysis, because it provides physically reasonable best-fit parameters including B_{c2}^{*ρ} at low temperatures, and captures more accurately the complexity of flux pinning, flux flow along channels, fluxon–fluxon interactions and superelectron quantum-tunnelling, as well as the normal-state properties and geometry of the important microstructural components.