Intrinsic superconducting properties and vortex dynamics in heavily overdoped Ba(Fe$_{0.86}$Co$_{0.14}$)$_2$As$_2$ single crystal

TL;DR

This study investigates the intrinsic superconducting parameters and vortex dynamics in heavily overdoped Ba(Fe$_{0.86}$Co$_{0.14}$)$_2$As$_2$ single crystals, revealing how these factors influence vortex behavior and pinning.

Contribution

It provides detailed measurements of superconducting parameters and analyzes vortex dynamics, highlighting the role of vortex core size and penetration depth in overdoped iron-based superconductors.

Findings

Superconducting critical temperature of 13.5 K

Magnetic penetration depth $ ightarrow$ 660 nm

Upper critical field anisotropy $ ightarrow$ 3.7

Abstract

In this work we report the influence of intrinsic superconducting parameters on the vortex dynamics in an overdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ (x=0.14) single crystal. We find a superconducting critical temperature of 13.5 K, magnetic penetration depth $\lambda_{ab}$(0) = 660 $\pm$ 50 nm, coherence length $\xi_{ab}$(0) = 5 nm, and the upper critical field anisotropy $\gamma_{T\rightarrow Tc}$ $\approx$ 3.7. In fact, the Ginzburg-Landau model may explain the angular dependent $H_{c2}$ 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 $\lambda$ play an important role in the resulting vortex dynamics in materials with similar intrinsic thermal fluctuations.