FeX₄ (X＝pnictogen, chalcogen) 正四面体構造を有する金属間化合物超伝導体ならびに類縁化合物の高圧下の単結晶育成

抄録

   In the first half of this article, the new material search for FeX₄ (X=pnictogen, chalcogen) based superconductors is introduced and the new method to grow single crystals for Fe-based superconductors and related materials are also described. Using a high-pressure apparatus, we report the single crystal growth of Fe-based superconductors and related materials (BaFe₂As₂, SrFe₂As₂, (Ba, Na)Fe₂As₂ and α-PbO type FeSe_0.9 superconductor, BaNi₂P₂). Especially, we have grown single crystals of BaNi₂P₂ superconductors from stoichiometric composition solutions for the first time. The temperature dependence of in-plane (r_//) and out-of-plane (r_⊥) resistivity for BaNi₂P₂ crystals were measured, the anisotropy ratio r_⊥/r_// is ~6.3 at 300 K, and sharp superconducting transition was observed at ~2.5 K.