Evaluation of a practical level of critical current densities in pnictides and recently discovered superconductors

Abstract

A dissipation-free current is one of the most fascinating and practically important properties of superconductors. At self-field conditions (when no external magnetic field is applied) dissipation-free current density, Jc(sf, T), in thin weak-link-free superconductors described by the equation (where λ(T) is the London penetration depth, and κ is the Ginzburg–Landau parameter) was proved for more than 90 superconductors, including type-I and type-II superconductors, elementary superconductors, pnictides, cuprates, MgB2, heavy fermions and H3S. In addition, it was recently proposed for quasi-two dimensional superconductors (namely pnictides and cuprates), that maximum achievable critical current density, Jc(sf, T ∼ 0 K), is linked with the transition temperature, Tc, and the mean spacing between superconducting sheets, d, by the following equation: (Talantsev and Crump 2018 Supercond. Sci. Technol. 31 124001). In this paper, we focused on the inverse problem, i.e., to find the best candidates for the developing practical wires in terms of their self-field critical current capacity from known parameters of newly discovered superconductors (for which we draw largely on Hosono et al 2015 Sci. Technol. Adv. Mater. 16 033503). Considering that in-field critical currents of iron-based superconductors are very slow functions of applied magnetic fields, our calculations may have wider applicability outside self-field conditions.