Pulsed laser deposition of CeO

SrTiO3 had been often tentatively used as an insulating barrier for HT superconductor/insulator heterostructures. Unfortunately, the deposition of SrTiO3 on the YBa2Cu3O7 inverse interface results in a poor epitaxial regrowth producing a high roughness dislocated titanate layer. Taking into account the good matching with YBa2Cu3O7 and LaAlO3, CeO2 and Ce1−xMxO2 (M = La, Zr), epitaxial layers were grown by pulsed laser deposition on LaAlO3 substrates and introduced into YBa2Cu3O7 based heterostructures as insulating barrier. After adjusting the growth parameters from RHEED oscillations, epitaxial growth is achieved, the oxide crystal axes being rotated by 45° from those of the substrate. The surface roughness of 250 nm thick films is very low with a rms value lower than 0.5 nm over 1 μm2. The YBa2Cu3O7 layers of a YBa2Cu3O7/CeO2 /YBa2Cu3O7 heterostructures grown using these optimized parameters show an independent resistive transition, when the thickness is larger than 25 nm, respectively at Tc1 = 89.6K and Tc2 = 91.4K