Surface roughness exponent and non-designed cap layer in PbZr0.53Ti0.47O3/La1.85Sr0.15CuO4 bilayers

The surface and interface roughness and roughness exponent of PbZr0.53Ti0.4 7O3 (PZT)/La1.85Sr0.15CuO4 bilayers deposited on SrTiO3 (001) substrates by rf/dc magnetron sputtering have been measured by x-ray reflectivity and di ffuse-scattering methods. We have found that the surface roughness increase s and the roughness exponent decreases with the increase of the thickness o f the PZT layers; and that there exist non-designed cap layers on the upper surfaces of the PZT layers. The growth character of the bilayer films is d iscussed.