Freestanding ferroelectric bubble domains*

Particle-like bubble domains typically form in ultra-thin ferroelectrics epitaxially clamped on flat substrates. Here, using first-principle-based simulations and local PFM measurements, we inquire if they can be as well sustained in free-standing films, which will be highly promising for some technologies. We demonstrate that these non-trivial dipolar patterns can indeed be retained in a freestanding state in ferroelectric membranes, despite the presence of inhomogeneously distributed structural ripples. We further shed some light on the origin of these latter structural ripples and analyze the stability as well as special features of free-standing polar bubbles.