Impact of the Spin Density Wave Order on the Superconducting Gap of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$

TL;DR

This study investigates how spin-density-wave order influences the superconducting gap in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, revealing a competition between these orders and their impact on electronic properties.

Contribution

It provides doping-dependent Raman scattering data showing the interplay between SDW and superconducting gaps in iron-pnictide superconductors.

Findings

Anisotropic superconducting gap at optimal doping

Reduction of pairing energy scale in coexistence region

Evidence of competition between SDW and SC orders

Abstract

We report a doping dependent electronic Raman scattering measurements on iron-pnictide superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals. A strongly anisotropic gap is found at optimal doping for x=0.065 with $\Delta_{max}\sim 5\Delta_{min}$. Upon entering the coexistence region between superconducting (SC) and spin-density-wave (SDW) orders, the effective pairing energy scale is strongly reduced. Our results are interpreted in terms of a competition between SC and SDW orders for electronic state at the Fermi level. Our findings advocate for a strong connection between the SC and SDW gaps anisotropies which are both linked to interband interactions.