Abstract
Magnetization and muon spin rotation and relaxation () measurements have been performed to study the superconducting and magnetic properties of . From magnetization measurements the lower and upper critical fields are found to be 8.5(1) mT and 1.44(2) T, respectively. Zero-field data show no sign of any magnetic ordering or weak magnetism. Transverse-field measurements in the vortex state provide the temperature dependence of the magnetic penetration depth . The temperature dependence of is consistent with the existence of a single -wave energy gap in the superconducting state of with a gap value of 0.82(2) meV at absolute zero temperature. However, a two-gap -wave model fit with gap values of 0.91(4) and 0.14(7) meV cannot be ruled out completely. The magnetic penetration depth at zero temperature is 291(3) nm. The ratio indicates that should be considered a strong-coupling superconductor.
- Received 24 March 2014
- Revised 24 September 2014
DOI:https://doi.org/10.1103/PhysRevB.90.144505
©2014 American Physical Society