Evaluation of current transport properties of GdBa₂Cu ₃O_7-δ coated conductors over a wide range of temperature and external magnetic fields

We have carried out detailed measurements on the electric field vs. current density (E-J) characteristics of GdBa₂Cu₃O _7-δ (GdBCO) coated conductors (CC) in a wide range of temperature and external magnetic fields. Four probe measurements were performed in a 20 T superconducting magnet system. Applying a constant electric field criterion, we have evaluated critical currents and n-values as a function of the temperature, the magnetic field and the field angle. Those results are relevant for the understanding of the practical performance of the tapes, and therefore to improve the process conditions effectively. The GdBCO CC was fabricated by the reel-to-reel PLD methods on the IBAD-MgO based substrate. The Self-field critical current per cm-width of the tape was above 400 A at 77 K. The results were also compared with our previous results on YBCO CC obtained from the similar deposition process. It is noted that the critical current of GdBCO CC is superior to those of previous YBCO CC over a wide range of practical external field and temperature.