Superconducting properties in heavily overdoped Ba(Fe0.86Co0.14)2As2 single crystals

Abstract

In this work we report the influence of intrinsic superconducting parameters on the vortex dynamics in an overdoped Ba(Fe1-xCox)2As2 (x=0.14) single crystal. We find a superconducting critical temperature of 13.5 K, magnetic penetration depth λab (0) = 660 ± 50 nm, coherence length ξab (0) = 5 nm, and the upper critical field anisotropy γT→Tc . 3.7. In fact, the Ginzburg- Landau model may explain the angular dependent Hc2 for this anisotropic three-dimensional superconductor. The vortex phase diagram, in comparison with the optimally doped compound, presents a narrow collective creep regime. In addition, we found no sign of correlated pinning along the c axis. Our results show that vortex core to defect size ratio and λ play an important role in the resulting vortex dynamics in materials with similar intrinsic thermal fluctuations.