Giant increase in critical current density of K${}_{x}$Fe${}_{2\ensuremath{-}y}$Se${}_{2}$ single crystals

Giant increase in critical current density of K $_{x}$ Fe $_{2 - y}$ Se $_{2}$ single crystals

Hechang Lei (雷和畅) and C. Petrovic

Phys. Rev. B 84, 212502 – Published 28 December 2011

Abstract

The critical current density $J_{c}^{a b}$ of K $_{x}$ Fe $_{2 - y}$ Se $_{2}$ single crystals can be enhanced by more than one order of magnitude, up to $\sim$ 2.1 $\times$ 10 $^{4}$ A/cm $^{2}$ by the post annealing and quenching technique. A scaling analysis reveals the universal behavior of the normalized pinning force as a function of the reduced field for all temperatures, indicating the presence of a single vortex pinning mechanism. The main pinning sources are three-dimensional (3D) point-like normal cores. The dominant vortex interaction with pinning centers is via spatial variations in critical temperature $T_{c}$ (“ $δ T_{c}$ pinning”).