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TT: Fachverband Tiefe Temperaturen

TT 69: Multiferroic Oxide Thin Films and Heterostructures II (joint session KFM/TT/MA)

TT 69.3: Vortrag

Mittwoch, 14. März 2018, 15:45–16:00, EMH 225

Controlling the effect of the depolarizing field in BaTiO₃-SrTiO₃ multilayers — •Nives Bonacic¹, Gabriele De Luca¹, Shovon Pal¹, Marco Campanini², Marta D. Rossell², Morgan Trassin¹, and Manfred Fiebig¹ — ¹ETH Zurich, Department of Materials — ²EMPA, Switzerland

The demand for ever-smaller devices has been approaching the fundamental limits of ultrathin ferroelectric films. In the low-thickness regime, maintaining a large, stable and switchable ferroelectric polarization relies on the control of the strain state, thickness, interface termination and electrostatic conditions. Achieving a robust polarization or a controlled domain state remains, however, challenging. Imperfect charge screening at interfaces results in non-cancellation of internal fields that can in extreme case annihilate ferroelectricity. Taking (BaTiO₃-SrRuO₃) capacitor-like heterostructures as a model system, we directly access the polarization and the domain state during the film deposition using optical second harmonic generation [1]. We observe a previously elusive impact of the evolving electrostatic environment on the BaTiO₃ domain state simultaneously with the growth. The initial phase of the top-electrode deposition is accompanied by temporary enhancement of built-in fields in the ferroelectric layer resulting in 180^∘ domain formation. We discuss ways to manipulate the depolarizing field and control the polarization during the growth as it presents a possible route towards a novel class of oxide-electronic devices. [1] G. De Luca et al., Nat. Commun. 1419 (2017).