Possible Sign-Reversing s-Wave Superconductivity in Co-Doped BaFe2As2 Proved by Thermal Transport Measurements

TL;DR

This study uses thermal transport measurements on Co-doped BaFe2As2 to provide evidence for sign-reversing s-wave superconductivity, revealing impurity effects and quasiparticle behavior in the superconducting state.

Contribution

It presents experimental evidence supporting the existence of sign-reversing s-wave pairing symmetry in Co-doped BaFe2As2 through thermal transport data.

Findings

Peak anomalies in thermal conductivity and Hall conductivity below Tc

Presence of a residual T-linear term indicating impurity-induced quasiparticles

Support for sign-reversing s-wave pairing symmetry

Abstract

Thermal transport measurements have been performed on single-crystalline Co-doped BaFe2As2 down to 0.1 K and under magnetic fields up to 7 T. Significant peak anomalies are observed in both thermal conductivity and thermal Hall conductivity below Tc as an indication of the enhancement of the quasiparticle mean-free path. Moreover, we find a sizable residual T-linear term in thermal conductivity, possibly due to a finite quasiparticle density of states in the superconducting gap induced by impurity pair breaking. Our findings support a pairing symmetry compatible with the theoretically predicted sign-reversing s-wave state.