Dependence of superconducting layer thickness on critical current density of IBAD/CVD-processed YBCO coated conductors

The thickness dependence of the critical current characteristics was investigated for YBa 2 Cu 3 O 7− δ (YBCO) coated conductors fabricated by Ion Beam Assist Deposition (IBAD)/Chemical Vapor Deposition (CVD) method in the range of 0.18–0.90 μm to find out the optimum thickness for various applications. The transport and magnetization critical current densities were estimated using the electric field criterion of E c = 1.0 × 10 −4 V/m and E c = 1.0 × 10 −9 V/m, respectively. The critical current density decreased with increase thickness in the low magnetic field region in the both electric field region because of the structural degradation of superconducting layer. This decreasing rate was lower than in Pulsed Laser Deposition (PLD)-processed YBCO coated conductors. It is found that the thickness dependence of irreversibility field B i differed between the low and normal electric field region. In the low electric field region, B i increased with increasing thickness. On the other hand, B i is almost independent of the thickness in the normal electric field region. The thickness dependence of B i was also superior to that of PLD-processed YBCO coated conductors.