Highly smooth and c-axis oriented superconducting MgB2 thin films were prepared by pulsed laser deposition with off-axis geometry. The films were deposited on Al2O3–C substrates perpendicularly aligned to a stoichiometric MgB2 target in a 120mTorr high purity Ar background gas. An in situ annealing was carried out at 650C for 60s in a 760Torr Ar atmosphere. Despite the short annealing time, an X-ray θ–2θ scan shows fairly good crystallization, according to the clear c-axis oriented peaks for the films. Both atomic force microscopy and the X-ray diffraction results indicated that the crystallite size was less than 50nm. The root-mean-square roughness of the off-axis film was about 4nm in a 5 x 5µm2 area. The TC,onset value of the best off-axis film reaches 33.1K with a narrow transition width of 0.9K. The films exhibited no anisotropy in HC2–T curves when parallel and perpendicular fields were applied. The slope of the HC2–T curves in the low field regime was 1T/K, which was among the highest reported values.

Off-Axis MgB2 Films Using an in situ Annealing Pulsed Laser Deposition Method. Y.Zhao, M.Ionescu, J.Horvat, S.X.Dou: Superconductor Science and Technology, 2005, 18, 395-9