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

Nanowires of Co-doped BaFe<formula><tex>$_{2}$</tex></formula>As<formula><tex>$_{2}$</tex></formula> have been realized and characterized. Thin films having thickness of 20 nm were grown on CaF<formula><tex>$_{2}$</tex></formula> (100) substrates by pulsed laser deposition. The films were then passivated in-situ with a thin layer of MgAl<formula><tex>$_{2}$</tex></formula>O<formula><tex>$_{4}$</tex></formula>. Using electron beam lithography, several submicron nanowire structures were patterned and electrically contacted to gold pads. The nanostructures have a superconducting critical temperature T<formula><tex>$_{c}$</tex></formula> of 16 K, for a 500 nm wide nanowire, and properties, in terms of normal state resistivity (0.3 m<formula><tex>$^{2}$</tex></formula> cm) and critical current (1 MA/cm<formula><tex>$^{2}$</tex></formula> 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.