Berlin 2018 – scientific programme
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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: Talk
Wednesday, March 14, 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).