Regensburg 2016 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 10: Focus Session: Ferroic Domain Walls III

DF 10.2: Vortrag

Mittwoch, 9. März 2016, 15:30–15:50, H25

Growth temperature as a tuning parameter for internal screening in ferroelectric thin films — •Christian Weymann, Céline Lichtensteiger, Stéphanie Fernandez-Pena, Jean-Marc Triscone, and Patrycja Paruch — DQMP, University of Geneva

In ferroelectric ultrathin films, the depolarization field arising from bound interface/surface charges must be compensated. This can be achieved by screening either by external screening, or by internal mobile charges from within the ferroelectric itself. In the absence of sufficient free charges, the ferroelectric can also form domains of opposite polarization.

Another frequently observed feature in ferroelectric thin films is built-in voltage, originating from asymmetrical screening, trapped charges, or strain gradients leading to flexoelectricity, and modifying the properties of the films. The resulting residual field will not only shift P-E hysteresis, but will also modify the intrinsic polarization configuration and domain stability.

By modulating the growth temperature of PbTiO₃ thin films, we engineered several series of ferroelectric samples with the same external electrical boundary conditions, but distinctively different internal screening. We used piezoresponse force microscopy to investigate the intrinsic domain configuration, written domain stability, and local ferroelectric switching loops of these samples. Our results open up a straightforward method to control the built-in field in such ferroelectric oxide thin films, which is crucial to applications.