Individual Evaluation of REBCO/Ag and Ag/Cu Interfacial Resistivities Inside Copper-Stabilized REBCO Tapes

The interfacial resistance at REBCO/Ag and Ag/Cu interfaces inside Rare-earth Barium Copper Oxide (REBCO) tapes is the main factor of joint resistance for well-fabricated copper-stabilized REBCO tape joints. There is no studies for individual evaluation of these two interfacial resistivities (interfacial resistance for unit area) in the same REBCO tape, though the individual resistance behavior is important for in-depth analysis of temperature and magnetic field dependence of the intrinsic resistance of REBCO tapes. In this study, we evaluated these two interfacial resistivities individually at 77 K and self-field with the contact-probing current transfer length (CTL) method. Numerical analysis showed that the individual evaluation is impossible by applying the method to copper-stabilized REBCO tapes. Therefore, first we measured the sum of interfacial resistivity at both the REBCO/Ag and Ag/Cu interfaces with a copper-stabilized REBCO tape, then measured that at the REBCO/Ag interface with the same REBCO tape whose Cu layer was removed etching solution. Experimental results indicated that the interfacial resistivity at the REBCO/Ag interface is smaller than that at the Ag/Cu interface. The temperature and magnetic field dependence of these two interfacial resistivities were also analyzed based on the results at 10–70 K and 0–15 T. The interfacial resistivity at the REBCO/Ag interface behaves similar to normal-conducting resistance of REBCO. This indicates that normal-conducting REBCO near the REBCO/Ag interface possibly affects the temperature and magnetic field dependence of the interfacial resistance.