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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 11: Focus Session: (Multi-)Ferroic States II

KFM 11.1: Vortrag

Dienstag, 19. März 2024, 09:30–10:00, EMH 225

Polar textures on silicon — •Catherine Dubourdieu — Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany — Freie Universität Berlin, Berlin, Germany

In nanoscale ferroelectrics, the polarization pattern depends on the chemical, mechanical and electrical boundary conditions and is the result of a delicate balance to minimize electrostatic energy costs associated with the depolarization field. In recent years, new exotic polar textures featuring curled polarization patterns (vortices, skyrmions, merons, etc...) have been unraveled in ultrathin films, superlattices or nanostructures. The development of topological nanoelectronics on chips that would take advantage of such polar nanodomains requires their integration on silicon. I will present in this talk the growth and the resulting polarization patterns of (BaTiO3/SrTiO3)n superlattices and of BaTiO3 nanoislands on silicon substrates. The epitaxy on Si of both types of heterostructures is realized by molecular beam epitaxy, which will be detailed. Based on X-ray diffraction, scanning transmission electron microscopy and piezoresponse force microscopy characterizations, I will discuss the strain state, the peculiar polar textures that develop in these systems and their response under electric field. The evidence of curled polarization nanodomains in the different BaTiO3-based heterostructures is a first step towards the integration of topological defects into nanoscale devices.

Keywords: BaTiO3; Ferroelectrics; Superlattices; Polar bubbles; Polar wave