Single Crystal Growth of the Fe-based Superconductor and Related Materials Using the High Pressure Synthesis

Abstract

   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.