We carried out the synchrotron X-ray diffraction measurements and investigated the oxygen octahedral distortions in compressively strained SrRuO3 epitaxial thin films on NdGaO3 substrates. We observed half-order Bragg reflections originating from the RuO6 octahedral distortions accommodated in the compressively strained films. Our structural analysis shows that the RuO6 octahedra are elongated along the out-of-plane direction and are rotated in the out-of-phase manner only about the out-of-plane direction. The RuO6 rotation angle γrot is 10.9° ± 1.2°, which is larger than that in the bulk SrRuO3. The results indicate that the substrate-induced compressive strain enhances the out-of-plane rotations while strongly suppressing the in-plane rotations. In fact, the half-order Bragg reflections arising from the octahedral rotations about the in-plane direction are found to be weak and broad, implying that the in-plane rotations exist only in the interface region, not in the entire film. This indicates that while the in-plane octahedral rotation propagates through the interfacial octahedral connections into the film, its propagation decays within the interface region because of the compressive strain. Our results indicate that both the substrate-induced strain and the interfacial octahedral connection play important roles in determining the octahedral distortions accommodated in the strained SrRuO3 films.
ASJC Scopus subject areas
- Physics and Astronomy(all)