Isothermal magnetization curves of a superconducting Nb film perforated by a square lattice of Ni dots exhibit quasiperiodic instabilities below approximately 4 K, with a field-dependent period equal to the first, second, or third matching fields. The instabilities are found in a range of applied fields well above the saturation matching value, and where a Nb film with the same dimensions and magnetization remained stable. The recovery of matching effects well below Tc approximately 8.8 K is unexpected, because strong flux gradients generated by the geometric barrier and random pinning suppress the formation of large domains of matched flux lines and dots. The results suggest that terraces of matched flux density may exist at the border of a flux-free zone near the film edge.
|Number of pages||7|
|Journal||Physica C: Superconductivity and its Applications|
|State||Published - May 2000|
|Event||1st Euroconference on Vortex Matter in Superconductors at Extreme Scales and Conditions - Crete, Greece|
Duration: Sep 18 1999 → Sep 24 1999
Bibliographical noteFunding Information:
Research at the University of Kentucky was supported by the U.S. Dept. Energy Office of Basic Energy Science, Division of Materials Science, Grant #DE-FG02-97ER45653. Research at Northwestern University was supported by the National Science Foundation under the Materials Research Center Grant #DMR-9309061. Research at the University of Wisconsin was supported by the U.S. Dept. Energy Division of High-Energy Physics, Grant #DE-FG02-96ER40961 and the NSF MRSEC for Nanostructured Materials.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering