Depairing current density of Ba0.5K0.5Fe1.95Co0.05As2 microbridges with nanoscale thickness

Abstract We investigated the depairing current density of Ba 0.5 K 0.5 Fe 1.95 Co 0.05 As 2 microbridges with width of 2 μm and thickness of 150 nm. The current vs. voltage characteristics of the microbridges show a Josephson-like behavior with the obvious hysteresis. The critical current density was observed as J c  = 7.9 MA/cm 2 at temperature 21 K, which is consistent with the Ginzburg–Landau depairing limit. However, the depairing current density is less than that of impurity-free crystal, although the Co ions provide additional pinning centers within the superconducting Fe 2 As 2 layers. The Co impurity also enhances the anisotropic factor of the critical current density by 1.3 (1 T) or 1.7 (3 T).