Abstract
The Meissner effect has been studied in and single crystals and compared to well known, type-II superconductors and . Whereas flux penetration is mostly determined by the bulk pinning (and, perhaps, surface barrier) resulting in a large negative magnetization, the flux expulsion upon cooling in a magnetic field is very small, which could also be due to pinning and/or surface-barrier effects. However, in stark contrast with the expected behavior, the amount of the expelled flux increases almost linearly with the applied magnetic field, at least up to our maximum field of 5.5 T, which far exceeds the upper limit for the surface barrier. One interpretation of the observed behavior is that there is a field-driven suppression of magnetic pair breaking.
- Received 22 October 2010
DOI:https://doi.org/10.1103/PhysRevB.82.180513
©2010 American Physical Society
Synopsis
Outstanding in the field
Published 19 November 2010
Iron arsenide superconductors exhibit a surprising capacity to prevent magnetic field penetration.
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