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
O2 (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
heterostructures grown using these
optimized parameters show an independent resistive transition, when the
thickness is larger than 25 nm, respectively at
= 89.6K and T