Although high-temperature superconductor cuprates have been discovered for more than 25 years, superconductors for high-field application are still based on low-temperature superconductors, such as Nb3Sn. The high anisotropies, brittle textures and high manufacturing costs limit the applicability of the cuprates.
Scientists from Brookhaven National Laboratory, Florida State University and Oak Ridge National Laboratory demonstrated that the iron superconductors, without most of the drawbacks of the cuprates, have a superior high-field performance over low-temperature superconductors at 4.2 K. With a CeO2 buffer, critical current densities >106 Acm−2 were observed in iron-chalcogenide FeSe0.5Te0.5 films grown on single-crystalline and coated conductor substrates.
These films are capable of carrying critical current densities exceeding 105Acm−2 under 30 tesla magnetic fields, which are much higher than those of low-temperature superconductors.
High critical current densities, low magnetic field anisotropies and relatively strong grain coupling make iron-chalcogenide-coated conductors particularly attractive for high-field applications at liquid helium temperatures.