High quality MgB 2 thin films in - situ grown by dc magnetron sputtering

Thin films of the recently discovered magnesium diboride (MgB2) intermetallic superconducting compound have been grown using a magnetron sputtering deposition technique followed by in-situ annealing at 830°C. High quality films were obtained on both sapphire and MgO substrates. The best films showed maximum Tc = 35 K (onset), a transition width of 0.5 K, a residual resisitivity ratio up to 1.6, a low temperature critical current density Jc > 10 A/cm and anisotropic critical field with γ ≅ 2.5 close to the values obtained for single crystals. The preparation technique can be easily scaled to produce large area in-situ films.