Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 17: Superconductivity: Thin Film Preparation

TT 17.2: Vortrag

Dienstag, 28. März 2006, 14:15–14:30, HSZ 02

New method to obtain superconducting Sr_1−xLa_xCuO₂ thin films by PLD — •V. Leca¹, G. Visanescu¹, G. Rijnders², D. H. A. Blank², S. Bals³, R. Kleiner¹, and D. Koelle¹ — ¹Physikalisches Institut–Experimentalphysik II, Univ. Tübingen, Germany — ²Univ. Twente, Faculty of Science and Technology, Enschede, The Netherlands — ³EMAT, Univ. Antwerp (RUCA), Antwerp,Belgium

Difficulties in fabricating single-phase infinite-layer (IL) type Sr_1−xLa_xCuO₂ thin films with good superconducting characteristics hampered the investigation of basic properties such as the pairing symmetry of this class of electron-doped superconducting cuprates. A new synthesis approach to obtain single-phase Sr_1−xLa_xCuO₂ (x = 0.10−0.175) thin films grown by pulsed laser deposition (PLD) on KTaO₃ and SrTiO₃ substrates will be presented. The IL phase is obtained after oxidation of the as-deposited oxygen-deficient Sr_1−xLa_xCuO_2−δ films having a 2√2a_p× 2√2a_p× c structure (a_p, c represent the perovskite subcell parameters). An increased stability of the IL phase for the entire studied La doping range (x=0.10-0.175) was achieved by applying this synthesis approach. Superconductivity was obtained for the x = 0.15−0.175 films, with the highest transition temperature T_c,zero = 17 K for x = 0.15. This result indicates a shift of the superconducting region towards a higher La doping level as compared to previous studies. For the Sr_1−xLa_xCuO₂ films grown on BaTiO₃/SrTiO₃, superconductivity was observed for x=0.15 only when the BaTiO₃ buffer layer is relaxed, following an in-situ annealing step, confirming that tensile strain is required in order to induce superconductivity in the Sr_1−xLa_xCuO₂ films.