Preparation of nano-scaled pinning centres in YBCO using PLD

Although the in-field critical current density J_c(B) of YBCO is high and promising for potential power applications, further enhancement in J_c is necessary. In higher magnetic fields, the intragrain pinning properties are the key point for enhancing J_c rather than grain boundaries [1].

Nano-scaled pinning centres are prepared in a quasi-multilayer approach using pulsed laser deposition. On-axis geometries as well as off-axis geometries are used within the IFW (Preparation of mixed REBCO films by Pulsed Laser Deposition). Films deposited by off-axis PLD show a very smooth surface and are therefore suitable for LT-STM pinning investigations (Pinning analysis using LT-SPM techniques).

Quasi-multilayers are prepared by doping YBCO with different materials:

1. Doping with pure (noble) metals (such as Ir) and internal formation of nanosized precipitates with the perovskite structure or
2. Doping with nanoparticles with good lattice matching with YBCO (such as Y₂O₃) and good chemical stability.

Fig. 1	Fig. 2

Fig. 1 shows XRD patterns for quasi-multilayers of YBCO/Y₂O₃ on (100) SrTiO₃.  The c-axis orientation for both YBCO and Y₂O₃ is evidenced by (00l) reflections. The intensity of Y₂O₃ clearly increases with pulse number. Figure 2 shows the increase of pinning force density and hence J_c in a Ir-doped YBCO sample compared to a standard YBCO film at 77K.

[1] Fernández, L. et al.  Phys. Rev. B 67, 052503 (2003).

Recent Publications

Hänisch, J., Cai, C., Stehr, V., Hühne, R., Lyubina, J., Nenkov, K., Fuchs, G., Schultz, L., Holzapfel, B.: "Formation and pinning properties of growth-controlled nanoscale precipitates in YBa₂Cu₃O_7-d/transition metal quasi-multilayers", Supercond. Sci. Technol. 19 (2006) 534-540

Hänisch, J., Cai, C., Hühne, R., Schultz, L., Holzapfel, B.: „Formation of nanosized BaIrO₃ precipitates and their contribution to flux pinning in Ir-doped YBa₂Cu₃O_7-δ quasi-multilayers“, Appl. Phys. Lett. 86 (2005) 122508

Cai, C., Hänisch, J., Hühne, R., Stehr, V., Mickel, C., Gemming, T., Holzapfel, B.: „Structural and magnetotransport properties of YBa₂Cu₃O_7-δ/Y₂O₃ quasimultilayers”, J. Appl. Physics 98 (2005) 123906