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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 10: Ferroics - Domains and Domain Walls

KFM 10.4: Vortrag

Dienstag, 2. April 2019, 10:15–10:30, H47

Transient depolarizing field effects leading to domain formation in the ultrathin regime — •Nives Strkalj¹, Gabriele De Luca¹, Marco Campanini², Shovon Pal¹, Jakob Schaab¹, Chiara Gattinoni¹, Nicola A. Spaldin¹, Marta D. Rossell², Manfred Fiebig¹, and Morgan Trassin¹ — ¹Department of Materials, ETH Zurich, Switzerland — ²EMPA, Switzerland

A major challenge for the ferroelectric-based device miniaturization is to stabilize a robust polarization. In the ultrathin regime, however, the interface-related effects can drastically alter the polarization behavior and in extreme case lead to annihilation of the ferroelectric state. Because the ferroelectric layers are usually grown below their Curie temperature, their polarization state is set during the heterostructure growth. We thus track the evolution of polarization state using in situ optical second harmonic generation [1]. Taking SrRuO₃-BaTiO₃-SrRuO₃ capacitor heterostructure as a model system, we observe an abrupt domain formation leading to a net polarization quench during the top electrode deposition. We show a reduced conductivity in the ultrathin regime of the top electrode, leading to an inferior charge screening efficiency and therefore transient depolarizing field enhancement [2]. We demonstrate a healing route to the single domain state by post-growth thermal annealing above the strain-engineered Curie temperature. Our in-situ approach addresses transient electrostatic effects during the deposition and sheds light on the emergence of complex domain architectures in ferroelectric superlattices. [1] G. De Luca et al. Nat. Commun. 8, 1419 (2017) [2] N. Strkalj et al. (submitted)