Synthesis and Characterization of BaFe₂As₂ Single Crystals Grown by In-flux Technique

We report a detailed characterization of BaFe₂As₂ single crystals grown by a metallic In-flux technique, an alternative to well-established growth routes using FeAs self- or Sn-flux. Electrical resistivity, magnetic susceptibility, nuclear magnetic resonance, and energy dispersive spectroscopy measurements showed no evidence of flux incorporation. More importantly, our results demonstrate that BaFe₂As₂ single crystals grown by In-flux have extremely high quality. To explore the efficiency of the In-flux growth method, we have also prepared nearly optimally doped superconducting samples of Ba(Fe_1-x M _x)₂As₂ (M = Co, Cu, Ni, and Ru). Among other interesting features, this alternative chemical substitution method has led to enhancement of the maximum T_c for most dopings.