Andreev Reflection Like Enhancement Above Bulk $T_c$ in Electron Underdoped Iron Arsenides

H. Z. Arham; C. R. Hunt; J. Gillett; S. D. Das; S. E. Sebastian; D. Y. Chung; M. G. Kanatzidis; L. H. Greene

Andreev Reflection Like Enhancement Above Bulk $T_c$ in Electron Underdoped Iron Arsenides

Superconductivity 2013-07-09 v1

Authors: H. Z. Arham , C. R. Hunt , J. Gillett , S. D. Das , S. E. Sebastian , D. Y. Chung , M. G. Kanatzidis , L. H. Greene

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Abstract

We use point contact spectroscopy (PCS) to probe the superconducting properties of electron doped $\rm{Ba(Fe_{1-x}Co_x)_2As_2}$ ( $\rm{x = 0.05, 0.055, 0.07, 0.08}$ ) and hole doped $\rm{Ba_{0.8}K_{0.2}Fe_2As_2}$ . PCS directly probes the low energy density of states via Andreev reflection, revealing two distinct superconducting gaps in both compound families. Apart from the electron underdoped $\rm{Ba(Fe_{1-x}Co_{x})_2As_2}$ , the excess current due to Andreev reflection for the compounds follows the typical BCS temperature dependence. For underdoped $\rm{Ba(Fe_{1-x}Co_{x})_2As_2}$ , the temperature dependence of the excess current deviates from that of BCS, developing a tail at higher temperatures and surviving above bulk $T_c$ . Possible explanations for this anomalous behavior are explored.

Keywords

Andreev reflection point contact spectroscopy iron arsenides superconducting gap excess current bulk Tc

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@article{arxiv.1307.1908,
  title  = {Andreev Reflection Like Enhancement Above Bulk $T_c$ in Electron Underdoped Iron Arsenides},
  author = {H. Z. Arham and C. R. Hunt and J. Gillett and S. D. Das and S. E. Sebastian and D. Y. Chung and M. G. Kanatzidis and L. H. Greene},
  journal= {arXiv preprint arXiv:1307.1908},
  year   = {2013}
}

Andreev Reflection Like Enhancement Above Bulk $T_c$ in Electron Underdoped Iron Arsenides

Abstract

Keywords

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