Characterization of FeSe single crystals

Hiroyuki Takeya, Shigeru Kasahara, Kazuto Hirata, Takashi Mochiku, Akira Sato, Yoshihiko Takano


5 被引用数 (Scopus)


Superconductivity at 8 K was reported in β-FeSe with a tetragonal PbO structure but not in δ-FeSe with a hexagonal NiAs structure. The superconducting transition temperature was then increased up to 37 K (on-set) by high pressure on polycrystalline samples. We report a study of the characterization on single crystals of FeSe superconductors. FeSe single crystals were grown using two methods, simple cooling from stoichiometric melt and flux using NaCl/KCl. While a ball-shaped aggregation composed of thick FeSe crystals was grown from the stoichiometric melt, thin hexagonal-shaped crystals with a size up to 1 mm were grown using the NaCl/KCl flux. The two different crystals indicated superconductivity around at 8 K in spite of their hexagonal shape, suggesting a non-superconducting compound with the NiAs-type hexagonal structure. According to the analyses using an X-ray diffractometer and a scanning electron microscope, the crystals contain microcracks that could be caused by stress. We assume that the hexagonal-shaped crystals grown at high temperature may turn partly to tetragonal β-FeSe at the β-δ structure transition temperature.

ジャーナルPhysica C: Superconductivity and its applications
出版ステータスPublished - 12月 2010

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学
  • エネルギー工学および電力技術
  • 電子工学および電気工学


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