Ferroelectrics are materials that exhibit a spontaneous switchable electric polarization.

In ferroelectric thin films, regions of uniform polarization, known as domains, can be controlled by tailoring the film thickness, electrostatic boundary conditions, deposition temperature, and epitaxial strain. The boundaries between domains are known as domain walls. In more complex structures, domains can further organize into larger-scale ordered arrangements termed superdomains, separated by superdomain walls, which can exhibit distinct structural and functional properties.

In this thesis, we investigate domain and superdomain structures in PbTiO₃-based heterostructures. We demonstrate that both domain and superdomain periodicities scale with the thickness of the ferroelectric layer, enabling control of their densities through thickness engineering. We further show that ferroelastic domains can propagate structural distortions into adjacent layers. Finally, beyond epitaxial thin films, we explore domains and superdomains in freestanding membranes, where substrate-induced constraints are removed.