Nano-bridges based on the superconducting MgB sub(2 thin films)

Precursor MgB thin films were prepared on sapphire substrates by magnetron sputtering. Influence of the ex situ annealing process on the roughness of the superconducting MgB sub(2 thin films is discussed. Optimized annealing process of MgB precursor thin films in vacuum results in smooth superconducting MgB) sub(2) thin films with roughness below 10 nm, critical temperature T sub(con = 31 K and transition width Delta T) sub(c) less than 1 K. Nano-bridges based on the superconducting MgB sub(2 thin films using optical and focused ion beam lithography were prepared. Critical current density j) sub(c) (4.2 K) measured on 50 nm wide strip was 7.3 x 10 super(6 A/cm) super(2) and no significant loss of superconducting properties was detected.