Co-doped BaFe$_{2}$As$_{2}$ Superconducting Nanowires for Detector Applications

Nanowires of Co-doped BaFe$_{2}$As$_{2}$ have been realized and characterized. Thin films having thickness of 20 nm were grown on CaF$_{2}$ (100) substrates by pulsed laser deposition. The films were then passivated in-situ with a thin layer of MgAl$_{2}$O$_{4}$. Using electron beam lithography, several submicron nanowire structures were patterned and electrically contacted to gold pads. The nanostructures have a superconducting critical temperature T$_{c}$ of 16 K, for a 500 nm wide nanowire, and properties, in terms of normal state resistivity (0.3 m$^{2}$ cm) and critical current (1 MA/cm$^{2}$ at 3 K), comparable with those of NbN nanowires. Moreover, they show localization effects in the normal state, while the current-voltage characteristics are dominated by flux creep.