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On the persistence of polar domains in ultrathin ferroelectric capacitors

Zubko, P; Lu, H; Bark, C-W; Martí, X; Santiso, J; Eom, C-B; Catalan, G; (2017) On the persistence of polar domains in ultrathin ferroelectric capacitors. Journal of Physics: Condensed Matter , 29 (28) , Article 284001. 10.1088/1361-648X/aa73c3. Green open access

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Abstract

The instability of ferroelectric ordering in ultra-thin films is one of the most important fundamental issues pertaining realization of a number of electronic devices with enhanced functionality, such as ferroelectric and multiferroic tunnel junctions or ferroelectric field effect transistors. In this paper, we investigate the polarization state of archetypal ultrathin (several nanometres) ferroelectric heterostructures: epitaxial single-crystalline BaTiO3 films sandwiched between the most habitual perovskite electrodes, SrRuO3, on top of the most used perovskite substrate, SrTiO3. We use a combination of piezoresponse force microscopy, dielectric measurements and structural characterization to provide conclusive evidence for the ferroelectric nature of the relaxed polarization state in ultrathin BaTiO3 capacitors. We show that even the high screening efficiency of SrRuO3 electrodes is still insufficient to stabilize polarization in SrRuO3/BaTiO3/SrRuO3 heterostructures at room temperature. We identify the key role of domain wall motion in determining the macroscopic electrical properties of ultrathin capacitors and discuss their dielectric response in the light of the recent interest in negative capacitance behaviour.

Type: Article
Title: On the persistence of polar domains in ultrathin ferroelectric capacitors
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/1361-648X/aa73c3
Publisher version: http://doi.org/10.1088/1361-648X/aa73c3
Language: English
Additional information: © 2017 IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords: Ultrathin barium titanate, tunnel junctions, ferroelectric domains, polarization screening, retention, negative capacitance
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: http://discovery.ucl.ac.uk/id/eprint/1561508
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