Broadening of X-ray reflections and inhomogeneous strain distribution in PbZrO3/SrRuO3/SrTiO3 epitaxial heterostructures

Antiferroelectric thin film heterostructures are important in energy storage technology and have prospective applications in domain wall nanoelectronics. The improvement of functional properties of this kind of material is directly connected with the effect of epitaxial strain. Thus, the investigations of strain distribution in the antiferroelectic films volume are on demand. In this work we have studied the distribution of orientational domain states and the condition of near-interface layer in a set of PbZrO3 films with different thickness grown on SrRuO3/SrTiO3 substrate. The analysis of X-ray diffraction curves shows that only the relatively narrow near-interface part of PbZrO3 film experiences significant strain along the normal to the surface, which decays very quickly on moving away from the interface. The out-of-plane strain profiles are strongly similar in films of different thickness above d=50 nm. The inhomogeneous out-of-plane strain is surprisingly of compressive character, which we attribute to the effects of hydrostatic-like compression associated with the presence of edge dislocations. In the films of higher thickness, we observe unusual broadening of the Bragg reflections, which is also tentatively associated with relaxation through the formation of dislocations.