Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Ferroics – Domains and Domain Walls 1

KFM 14.3: Vortrag

Mittwoch, 7. September 2022, 10:10–10:30, H5

Continuous polarization control at nanoscopic dimensions — •Martin F. Sarott¹, Marta D. Rossell², Manfred Fiebig¹, and Morgan Trassin¹ — ¹Department of Materials, ETH Zurich, Switzerland — ²Electron Microscopy Center, Empa Swiss Federal Laboratories for Materials Science and Technology, Switzerland

The switchable bistable polarization in ferroelectrics allows for the binary control of optical, electronic, and catalytic properties. Going beyond the limitation of a binary remanent polarization holds great promise for emerging neuromorphic concepts. Here, we demonstrate that we can arbitrarily set the magnitude of the remanent ferroelectric polarization at the nanoscale in epitaxial PbZr0.52Ti0.48O3 thin films with a single DC bias. By approaching the PZT morphotropic phase boundary, we achieve a high degree of control over this unusually susceptible system via epitaxial strain. We employ this to accomplish the formation of decoupled nanometric 180^∘ domains with a broad coercive field distribution. Using in-situ optical second harmonic generation and X-ray diffraction, we study the emergence of the nanoscopic domain configuration. We then use piezoresponse force microscopy to demonstrate the ability to locally and reversibly modulate the remanent polarization continuously between depolarized and saturated, while preserving the nanoscopic length scale of the domains. We highlight the technological relevance of nanoscale non-binary polarization switching, by showing (i) the voltage-controlled tunability of the nonlinear optical response and (ii) the quasi-continuous tunability of the tunnel electroresistance in ferroelectric tunnel junctions.