Direct observation of the depairing current density in single-crystalline Ba0.5K0.5Fe2As2 microbridge with nanoscale thickness

We investigated the critical current density (Jc) of Ba0.5K0.5Fe2As2 single-crystalline microbridges with thicknesses ranging from 276 to 18 nm. The Jc of the microbridge with thickness down to 91 nm is 10.8 MA/cm2 at 35 K, and reaches 944.4 MA/cm2 by extrapolating Jc(T) to T = 0 K using a two-gap s-wave Ginzburg-Landau model, well in accordance with the depairing current limit. The temperature, magnetic field, and angular-dependence of Jc(T,H,θ) indicated weaker field dependence and weakly anisotropic factor of 1.15 (1 T) and 1.26 (5 T), which also yielded the validity of the anisotropic Ginzburg-Landau scaling.