Basic and Pinning-Relevant Properties of Superconductors
Although the in-field critical current density Jc(B) of YBCO is high and promising for potential power applications, further enhancement in Jc is necessary. In higher magnetic fields, the intragrain pinning properties are the key point for enhancing Jc rather than grain boundaries .
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. Films deposited by off-axis PLD show a very smooth surface and are therefore suitable for LT-STM pinning investigations.
Quasi-multilayers are prepared by doping YBCO with different materia
- Doping with pure (noble) metals (such as Ir) and internal formation of nanosized precipitates with the perovskite structure or
- 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 Jc in a Ir-doped YBCO sample compared to a standard YBCO film at 77K.
 Fernández, L. et al. Phys. Rev. B 67, 052503 (2003).
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 YBa2Cu3O7-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 YBa2Cu3O7-? 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 YBa2Cu3O7-?/Y2O3 quasimultilayers”, J. Appl. Physics 98 (2005) 123906