As-grown magnesium diboride superconducting thin films deposited by pulsedlaser deposition

As-grown superconducting MgB2 thin films were deposited by pulsed laser dep osition on magnesium oxide and sapphire substrates. Starting from a non-sto ichiometric, Mg and B mixed-powder target, we were able to grow the superco nducting phase during the film deposition, without any further annealing pr ocess. So far, samples grown in the temperature range of 400-450 degreesC, and at an argon buffer pressure of the order of 10(-2) mbar turned out to b e superconducting with an onset temperature of the resistive transition at about 25 K. Even if the deposition process still needs to be fully optimize d, we have demonstrated that this method allows us to achieve in situ depos ition of as-grown superconducting thin films. This procedure could therefor e be promising for the deposition of high-quality epitaxial MgB2 thin films .