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arXiv · 1007.5086

Measurement of a Sign-Changing Two-Gap Superconducting Phase in Electron-Doped Ba(Fe_{1-x}Co_x)_2As_2 Single Crystals using Scanning Tunneling Spectroscopy

M. L. Teague·G. K. Drayna·G. P. Lockhart·P. Cheng·B. Shen·H. -H. Wen·N. -C. Yeh
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Abstract

Scanning tunneling spectroscopic studies of $Ba(Fe_{1-x}Co_x)_2As_2$ (x = 0.06, 0.12) single crystals reveal direct evidence for predominantly two-gap superconductivity. These gaps decrease with increasing temperature and vanish above the superconducting transition $T_c$. The two-gap nature and the slightly doping- and energy-dependent quasiparticle scattering interferences near the wave-vectors $(\pm π, 0)$ and $(0, \pm π)$ are consistent with sign-changing $s$-wave superconductivity. The excess zero-bias conductance and the large gap-to-$T_c$ ratios suggest dominant unitary impurity scattering.

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M. L. Teague, G. K. Drayna, G. P. Lockhart, P. Cheng, B. Shen, H. -H. Wen, N. -C. Yeh. 2011-01-30. Measurement of a Sign-Changing Two-Gap Superconducting Phase in Electron-Doped Ba(Fe_{1-x}Co_x)_2As_2 Single Crystals using Scanning Tunneling Spectroscopy. https://doi.org/10.1103/physrevlett.106.087004

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