Temperature dependence of transport critical current density for REBCO superconducting tapes deposited by MOCVD

Abstract The temperature-dependent transport critical current density ( J c ) behavior of REBa 2 Cu 3 O 7− δ (REBCO) superconducting tapes with various RE substitutions and combinations has been systematically studied in the temperature range of 4 K–77 K. The measured J c values were found to be highly in accordance with J c T , B = J c ( 0 K , B ) ( 1 − T / T c ) s with the values of the exponent coefficients s ranging from 1.9 to 2.6 in the magnetic-field range of 1–5 T depending on RE ion(s), revealing the dominative pinning mechanism of flux core pinning. The RE-ionic-radius ( r ) dependences of J c T , B showed reversed trends for temperatures below and above 50 K, with J c increasing with r at higher temperatures while it decreased with r at lower temperatures, which was consistent with previously reported results. In particular, the in-field J c of REBCO tapes at 4 K as a function of r was consistent with the J c – r trend for low temperatures. We propose to attribute the J c – r trends to the higher charge carrier density and the lower critical transition temperature (