1202.3837 (Toshinori Ozaki et al.)

One-step synthesis of K0.8Fe2Se2 single crystals for high critical
current density    [PDF]

Toshinori Ozaki, Hiroyuki Takeya, Hiroyuki Okazaki, Keita Deguchi, Satoshi Demura, Yasuna Kawasaki, Hiroshi Hara, Tohru Watanabe, Takahide Yamaguchi, Yoshihiko Takano

We have established a simple process that allows for the one-step synthesis
of K0.8Fe2Se2 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 \Box_0Hc2(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\times10^5 and 3.4\times10^4 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 K0.8Fe2Se2 is a promising candidate material for practical
applications.

View original: http://arxiv.org/abs/1202.3837