Speaker
Description
Maximizing critical current density (Jc) and minimizing flux creep in high temperature superconductors (HTS) is critical for their inclusion in accelerator magnets where both high magnitude and high stability magnetic fields are required. In YBa2Cu3O7-x (YBCO) thin films, critical current density can be enhanced by either the addition of many shallow pinning centers or the addition of fewer, deeper pins. In contrast, flux creep is better managed by the addition of deep pins. Pulsed laser deposition (PLD) was utilized to fabricate YBCO thin films on SrTiO3 (STO) substrates with two different, non-reacting, and insulating phase additions: BaZrO3 (BZO) and Y2BaCuO5 (Y211). Targets utilized in the PLD process consisted of YBCO doped with 2 vol. % BZO, and YBCO doped with 0, 5, 10, and 15 vol. % Y211. XRD and TEM characterization was performed. Magnetic Jc (B,T,) properties were determined. Additionally, the magnetic relaxation of the samples was measured at fields from 0-8 T and at temperatures of 4.2 to 77 K. The results of these measurements were used to generate U(J) vs. J curves for each sample; fits were performed to extract an intrinsic pinning potential (U0). These data were compared with high resolution XRD and TEM data on these uniquely hetero-structured YBCO films to elucidate structure-property relationships.
