Growths of MgB2 thin films by pulsed laser deposition

The recent discovery of metallic-like superconductivity in bulk MgB₂ material [1] opened a new class of possible applications in current transport, magnetic field devices and electronic devices. Fabrication of thin films in situ is essential in order to explore the device applications of this material, and in spite of a few reports [2], [3], [4], this still remains a challenge. The main reasons for this are the high vapour pressure of Mg even at low temperatures, and the high susceptibility of Mg to oxidation. A number of c-axis oriented MgB₂ films were grown on Al₂O₃-R cut, and the stoichiometry of the films was measured by ICP as a function of deposition pressure and laser fluence. It was found that the relative concentration of Mg on the substrate varies considerably with pressure and laser fluence. A relative concentration of around 53 at% Mg, which is necessary in order to form stoichiometric MgB₂ phase, can be obtain only in a narrow range of deposition pressures and laser fluences. The films obtain under these conditions were characterised by X-ray diffraction and magnetic moment in applied fields up to 9T.