Magnetic Relaxation in Commercial REBCO Tapes With and Without Artificial Pinning Centers

High-temperature superconducting REBCO tapes are expected to be applied to next-generation magnets for their high current density. One of their problems in the magnet application is the magnetic field instability caused by the decay of magnetization due to the shielding current caused by the tape shape. Therefore, it is important to evaluate the magnetization relaxation of REBCO tapes for the magnet design. In this study, we evaluated the magnetization relaxation of commercial REBCO tapes with and without APCs from Fujikura, SuperPower, and SuperOx in a wide temperature and field range. As a result, at low temperatures below 20K, there was negligible change, but at medium and above temperatures, the change due to the introduction of APC was different for each providers. By discussing the temperature dependence based on the flux creep model and the double kink excitation model, we explained why magnetization relaxation occurs, which is necessary for magnet design.