The influence of la substitution and oxygen reduction in ambipolar La-doped YBa2Cu3Oy thin films

Abstract

We report hole and electron doping in Y0.38La 0.62(Ba2-xLax)Cu3Oy thin films synthesized by the pulsed laser deposition technique and subsequently annealed in oxygen ambient or in a vacuum. X-ray diffraction studies suggested a single phase in p-type thin films and transport measurements showed a superconductor-to-insulator transition at x = 0.46. Hall measurements indicated electrons were successfully doped when the thin films were annealed in vacuum. The n-type samples demonstrated metallic behaviour within moderate temperature ranges, and a low in-plane resistivity (ρab) and a high carrier density for 0.32 ≤ x ≤ 0.46. The increase in ρab for higher La doping levels, probably caused by charge compensation, is also discussed. The present result could be a significant step in searching for electron-doped superconductivity in the YBa2Cu3Oy system. © 2012 IOP Publishing Ltd.