We have investigated the effect of substrate thermal conductivity on dendritic flux formation in thin superconducting YBa 2Cu 3O7−x films grown on yttrium-stabilized zirconia, SrTiO 3, MgO, and sapphire, exploiting a recently developed ultra-fast magneto-optical imaging system and its ultra-fast field ramp (3 kT/s). Dendritic flux formation triggered solely by rapid ramping of the external field is reported for the first time in YBCO on yttrium-stabilized zirconia, the substrate with the lowest thermal conductivity. For the other substrates, the dendritic instability could be generated only after introducing an artificial defect at the edge, enhancing the local induction. We find that the upper temperature threshold for the appearance of dendrites depends on the thermal conductivity of the substrate.
Bibliographical noteFunding Information:
The authors thank Dr. Robert Semerad for preparing samples and helpful discussions. We acknowledge a partial financial support from the Israel Science Foundation (Grant No. 164/12) and the Norwegian Research Council.
© 2014, Springer Science+Business Media New York.
- Dendritic flux instability
- High temperature superconductors (HTS)
- Thermal conductivity
- Ultra-fast magneto-optical (MO) imaging