Intrinsic superconducting transport properties of ultra-thin Fe1+yTe0.6Se0.4 microbridges

We investigated the superconducting properties of Fe 1+ y Te 0.6 Se 0.4 single-crystalline microbridges with a width of 4 μm and thicknesses ranging from 20.8 to 136.2 nm. The temperature-dependent in-plane resistance of the bridges exhibited a type of metal-insulator transition in the normal state. The critical current density ( J c ) of the microbridge with a thickness of 136.2 nm was 82.3 kA/cm 2 at 3K and reached 105 kA/cm 2 after extrapolation to T = 0 K. The current versus voltage characteristics of the microbridges showed a Josephson-like behavior with an obvious hysteresis. These results demonstrate the potential application of ultra-thin Fe-based microbridges in superconducting electronic devices such as bolometric detectors.