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arXiv · 0909.4855

Thermal conductivity study of KFe$_2$As$_2$ single crystal: clear evidence for unconventional superconducting gap with nodes

J. K. Dong·S. Y. Zhou·T. Y. Guan·H. Zhang·Y. F. Dai·X. Qiu·X. F. Wang·Y. He·X. H. Chen·S. Y. Li
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Abstract

The in-plane resistivity $ρ$ and thermal conductivity $κ$ of extremely overdoped KFe$_2$As$_2$ ($T_c$ = 3.0 K) single crystal were studied. It is found that $ρ\sim T^{1.5}$ at low temperature, a typical non-Fermi liquid behavior of electrons scattered by antiferromagnetic spin fluctuations. In zero field, we observed a large residual linear term $κ_0/T$, about one third of the normal-state value. In low magnetic fields, $κ_0/T(H)$ increases very fast. Such a behavior of $κ_0/T$ mimics the d-wave cuprate superconductors, therefore provides clear evidence for nodes in the superconducting gap of KFe$_2$As$_2$. Based on the Fermi surface topology of KFe$_2$As$_2$, it is believed that the dominant intraband pairing via antiferromagnetic spin fluctuations results in the unconventional superconducting gap with nodes.

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J. K. Dong, S. Y. Zhou, T. Y. Guan, H. Zhang, Y. F. Dai, X. Qiu, X. F. Wang, Y. He, X. H. Chen, S. Y. Li. 2009-10-15. Thermal conductivity study of KFe$_2$As$_2$ single crystal: clear evidence for unconventional superconducting gap with nodes. https://arxiv.org/abs/0909.4855

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