Critical current density and mechanism of vortex pinning in KxFe2-ySe2 doped with S

Abstract

We report the critical current density Jc in KxFe2-ySe2-zSz crystals. The Jc can be enhanced significantly with optimal S doping (z=0.99). For K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2), the weak fishtail effect is found for H||c. The normalized vortex pinning forces follow the scaling law with a maximum position at 0.41 of the reduced magnetic field. These results demonstrate that the small size normal point defects dominate the vortex pinning mechanism.

4 pages, 5 figures

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• Evolution of the Pauli spin-paramagnetic effect on the upper critical fields of K${}_x$Fe${}_{2-y}$Se${}_{2-z}$S${}_z$ single crystals
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