One-step synthesis of KxFe2−ySe2 single crystal for high critical current density Toshinori Ozaki, Hiroyuki Takeya, Hiroyuki Okazaki, Keita Deguchi, Satoshi Demura, Yasuna Kawasaki, Hiroshi Hara, Tohru Watanabe, Takahide Yamaguchi and Yoshihiko Takano EPL, 98 2 (2012) 27002 Published online: 20 April 2012 DOI: 10.1209/0295-5075/98/27002