One-step synthesis of KxFe2−ySe2 single crystal for high critical current density
National Institute for Materials Science - 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
2 JST, Transformative Research-Project on Iron Pnictides (TRIP) - Chiyoda, Tokyo 102-0075, Japan
3 University of Tsukuba - 1-1-1 Tennodai, Tsukuba, Ibaraki 305-0001, Japan
Accepted: 16 March 2012
We have established a simple process that allows for the one-step synthesis of KxFe2−ySe2 single crystals, which exhibit high critical current density Jc. The post annealing and quenching technique has improved the homogeneity of as-grown crystals, resulting in full shielding of the external magnetic field. The quenched crystals show a superconducting transition at Tconset=32.9 K and Tczero=32.1 K. The upper critical fields μ 0 H02 (0) for H∥ab and H∥c are estimated to be ∼206 and ∼50 T, respectively. The critical current densities Jc for H∥ab and H∥c reach as high as 1.0×105 and 3.4×104 A/cm2 at 5 K. Furthermore, Jc exhibits a high field performance and a significantly weak temperature dependence up to 5 T, suggesting strong pinning. These results demonstrate that KxFe2−ySe2 would be a promising candidate material for practical applications.
PACS: 74.70.Xa – Pnictides and chalcogenides / 74.25.Sv – Critical currents / 74.25.Ha – Magnetic properties including vortex structures and related phenomena
© EPLA, 2012