Abstract
The radio frequency penetration depth was measured in the superconductor under pulsed magnetic fields extending to 60 T and down to 14 K. Using these data we are able to infer a , phase diagram, for applied fields parallel and perpendicular to the crystallographic axis. The upper critical-field curvature is different for the respective orientations, but they each remains positive down to 14 K. The upper critical-field anisotropy is moderate, close to , and drops with the decrease in temperature, reaching at 14 K. These data and analysis indicate that (i) anisotropy diminishes with temperature and has an unusual temperature dependence and (ii) for this compound may easily approach fields of 75 T.
- Received 28 July 2008
DOI:https://doi.org/10.1103/PhysRevB.78.220505
©2008 American Physical Society