Apr 10, 2025
9:15am - 9:45am
Summit, Level 4, Room 433
Catherine Dubourdieu1,2
Helmholtz-Zentrum Berlin für Materialien und Energie1,Freie Universität Berlin2
Ferroelectric polar textures are characterized by regions with distinct polarization orientations, forming complex structures such as vortices, skyrmions or hopfions. Understanding and controlling topological polar textures open up exciting possibilities for advanced applications in memories, logic devices or sensors. So far, all monolithically grown polar textures have been realized on oxide substrates (such as SrTiO
3 or scandates), which limits their applicability. I will present in this talk the stabilization of polar textures in (BaTiO
3/SrTiO
3)n superlattices epitaxially grown on silicon. A major difference with superlattices grown on oxide substrates is the tensile strain, which is imparted by the Si substrate upon cooling from the growth temperature down to room temperature. The superlattices were synthesized by molecular beam epitaxy. Various BaTiO
3 and SrTiO
3 thicknesses, in the range of 2-5 nm, were investigated. Advanced scanning transmission electron microscopy methods were used to map the Ti-atom displacements and to determine the strain landscape. These local analyses were complemented by synchrotron X-ray diffraction. Periodic textures such as alternating a/c domains, vortices and polar waves will be discussed for the different layer thicknesses, as well as the strain state associated to them. The evolution of the polar domains with temperature will be presented.