Single Crystal Growth and Characterization of the Iron-Based Superconductor KFe2As2 Synthesized by KAs Flux Method
Centimeter-sized platelet single crystals of KFe 2 As 2 were grown using a self-flux method. An encapsulation technique using a commercial stainless steel container allowed the stable crystal growth to last for more than 2 weeks. Ternary K–Fe–As systems with various starting compositions were examined to determine the optimal growth conditions. The employment of KAs flux led to the growth of large single crystals with a typical size of as large as 15 ×10 ×0.4 mm 3 . The grown crystals exhibit a sharp superconducting transition at 3.4 K with the transition width 0.2 K, as well as the very large residual resistivity ratio exceeding 450, evidencing the good sample quality.