Upper critical fields and critical current densities of Fe-based superconductors as compared to those of other technical superconductors

► Upper critical fields are extremely high and weakly anisotropic. ► Coherence lengths are of the order of the nanometre in the T = 0 limit. ► Critical currents are high, nearly isotropic and almost field independent at low T. ► Grain boundaries have a current limiting effect, as in YBCO. ► Wires, tapes and coated conductors based on FeSC are being developed.