Dresden 2017 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 11: Ferroics - Domains, Domain Walls and Skyrmions II

DF 11.2: Talk

Wednesday, March 22, 2017, 10:00–10:15, WIL B321

Probing in situ the polar states in growing multiferroic heterostructures — •Morgan Trassin, Gabriele De Luca, Sebastian Manz, and Manfred Fiebig — ETH Zurich, Switzerland

In ferroelectric thin films, the polarization state, i. e. orientation and domain architecture, defines the macroscopic ferroelectric properties such as the switching dynamics. Ferroelectric domain engineering is in permanent evolution from the epitaxial strain tuning to the chemical control on interface atomic termination. Technology promising complex polar flux closure or vortices architecture have been recently demonstrated in ferroelectric heterostructures. However the determination of the role of depolarizing field and local strain in the formation of these complex polar states remains challenging. The optical second harmonic generation process is an efficient and non-invasive tool for thin films ferroic properties probing. Here, we investigate the emergence of the ferroelectric polarization in ultra-thin ferroelectric and multiferroic films and monitor in situ the optical non-linear response of the film during the growth. We find that, the ferroelectric critical thickness and domain state can be measured in situ during the film deposition. Using a combination of epitaxial strain engineering and surface termination control in (BiFeO₃/SrRuO₃)_n multilayers, we determine the BiFeO₃ net polarization orientation in each layer and in real-time, exempt from substrate contribution. Our work provides direct observation of ferroelectric states during the growth as well as new insights towards further control of ferroelectric based heterostructure.