Magneto-optical imaging and transport properties of FeSe superconducting   tapes prepared by diffusion method
  High-quality FeSe tapes have been prepared by using a diffusion method. By adjusting the reaction temperature and the thickness systematically, a transport critical current density as high as 600 A/cm2 at 4.2 K under self field is achieved. Magneto-optical images indicate considerable distribution of Tc and weak-link features in the FeSe tape. This study gives some insight into how to improve the quality and performance of FeSe tapes and other superconducting tapes prepared through diffusion method further. 
Q. P. Ding, S. Mohan, Y. Tsuchiya, T. Taen, Y. Nakajima, and T.   Tamegai
cond-mat.supr-con