IMF2017

Domains in ferroelectric materials have been the subject of many years of research. Originally considered detrimental for ferroelectric thin films and undesirable for applications which require polarisation stability, the novel properties of domains and their boundaries, domain walls, have sparked scientific interest in their functionality and possible applications. Domain walls have been shown to enhance the properties of ferroelectrics and exhibit symmetry different to the bulk material, making multidomain ferroelectrics a pathway towards novel device implementations through domain wall nanoelectronics. Here we present results of synchrotron X-ray diffraction studies on PbTiO₃/SrTiO₃ superlattices. We look at the behaviour of ferroelectric domains in these materials across the ferroelectric phase transition. We discover a transition during which the domain walls change their orientation, from walls aligned along the <100> crystallographic axes at room temperature, to walls oriented along the <110> axes at higher temperatures and study this reorientation for different domain periods. Using a nanofocused beam, we map the real space distributions of these domains, providing the first non-invasive real space observations of buried domains in ferroelectric/dielectric superlattices. By mapping the domain orientations in the vicinity of a defect, we show that domain walls align along the edges of features in the topography of the thin film. We map the distribution of film lattice parameters around one of these features and we show that this alignment is associated with strain and large strain gradients. These findings offer a greater insight on how to control the orientations of domain walls in multidomain ferroelectric materials.