Anomalous impurity effects in the iron-based superconductor KFe$_2$As$_2$

A. F. Wang; S. Y. Zhou; X. G. Luo; X. C. Hong; Y. J. Yan; J. J. Ying; P. Cheng; G. J. Ye; Z. J. Xiang; S. Y. Li; X. H. Chen

doi:10.1103/PhysRevB.89.064510

paper

Anomalous impurity effects in the iron-based superconductor KFe $_{2}$ As $_{2}$

arXiv:1206.2030 · doi:10.1103/PhysRevB.89.064510

Abstract

High-quality K(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ As $_{2}$ single crystals have been grown by using KAs flux method. Instead of increasing the superconducting transition temperature $T_{c}$ through electron doping, we find that Co impurities rapidly suppress $T_{c}$ down to zero at only $x \approx$ 0.04. Such an effective suppression of $T_{c}$ by impurities is quite different from that observed in Ba $_{0.5}$ K $_{0.5}$ Fe $_{2}$ As $_{2}$ with multiple nodeless superconducting gaps. Thermal conductivity measurements in zero field show that the residual linear term $κ_{0} / T$ only change slightly with $3.4%$ Co doping, despite the sharp increase of scattering rate. The implications of these anomalous impurity effects are discussed.

5 pages, 4 figs

Anomalous impurity effects in the iron-based superconductor KFe2​As2​

Abstract

Anomalous impurity effects in the iron-based superconductor KFe $_{2}$ As $_{2}$