Keywords: 
• Ba1-xKxFe2As2 /
• 磁通钉扎势 /
• 钉扎机理

Abstract: The discovery of superconductivity in iron-based superconductors by Professor Hosono in Japan in 2008 has triggered off an enormous group of researches the world wide. The iron-based superconductors are regarded as another kind of high-Tc superconductors, which possess lots of merits, such as very high upper critical field (Hc2), high critical current density (Jc), and small crystal anisotropy (γ), are promising for high field applications. Ba1?xKxFe2As2, as a typical FeAs-122 superconductor, is focused on by both theoretical physicists and material scientists since its discovery. In this paper, we first successfully fabricate Ba1?xKxFe2As2 single crystal. It has an onset transition temperature up to 38.5 K, while its zero resistivity temperature reaches 37.2 K. Both the R-T and M-T data of it show very sharp superconducting transition, and its critical current density at 5 K and self field is over 106 A·cm?2 and almost field independent. The flux pinning force and the relative pinning mechanisms in Ba1?xKxFe2As2 are discussed by analyzing the data obtained from the measurements about the R-T and M-H under different conditions. Results indicate that the Ba1?xKxFe2As2 superconductors have very strong intrinsic vortex pinning force, and the vortex potentials (U0) under 9 T field are 5800 K and 8100 K for the H//c and H//ab, respectively. Furthermore, the vortex pinning mechanism is also investigated by analyzing the relationship Jc-B. According to the present results, the flux pinning mechanism should beδ(l) pinning because of the change of mean free path for electrons induced by nano-size crystallographic defects in Ba1?xKxFe2As2.