Direct Observation of Microstructures on Superconducting Single Crystals of K$_x$Fe$_{2-y}$Se$_2$

Masashi Tanaka; Hiroyuki Takeya; Yoshihiko Takano

doi:10.7567/APEX.10.023101

Direct Observation of Microstructures on Superconducting Single Crystals of K$_x$Fe$_{2-y}$Se$_2$

Superconductivity 2017-01-06 v2

Authors: Masashi Tanaka , Hiroyuki Takeya , Yoshihiko Takano

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Abstract

Potassium intercalated FeSe has been reported as a superconductor with superconducting transition temperatures ( $T_{\rm c}$ 's) of 30-48 K. However, there is no clear answer to identify the relationship between the surface morphology, compositional ratio and its crystal structure. This report directly reveals the correspondence among these three characteristics in single crystals with a $T_{\rm c}$ onset of around 44 K using a micro-sampling technique. Island-like parts on the surface of the crystals clearly have the K $_x$ Fe $_2$ Se $_2$ structure with perfect FeSe layers, which is formed in conjunction with the K $_2$ Fe $_4$ Se $_5$ phase. This results in the appearance of the $T_{\rm c}$ onset of 44 K.

Keywords

superconducting single crystals K$_x$Fe$_{2-y}$Se$_2$ microstructures potassium intercalated FeSe surface morphology crystal structure

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@article{arxiv.1609.03151,
  title  = {Direct Observation of Microstructures on Superconducting Single Crystals of K$_x$Fe$_{2-y}$Se$_2$},
  author = {Masashi Tanaka and Hiroyuki Takeya and Yoshihiko Takano},
  journal= {arXiv preprint arXiv:1609.03151},
  year   = {2017}
}

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15 pages, 6 figures

Direct Observation of Microstructures on Superconducting Single Crystals of K$_x$Fe$_{2-y}$Se$_2$

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