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A rhombohedral ferroelectric phase in epitaxially strained Hf0.5Zr0.5O2 thin films

Wei, Y., Nukala, P., Salverda, M., Matzen, S., Zhao, H. J., Momand, J., Everhardt, A. S., Agnus, G., Blake, G. R., Lecoeur, P., Kooi, B. J., Iniguez, J., Dkhil, B. & Noheda, B., Dec-2018, In : Nature Materials. 17, 12, p. 1095-1100 7 p.

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  • A rhombohedral ferroelectric phase in epitaxially strained Hf0.5Zr0.5O2 thin films

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Hafnia-based thin films are a favoured candidate for the integration of robust ferroelectricity at the nanoscale into next-generation memory and logic devices. This is because their ferroelectric polarization becomes more robust as the size is reduced, exposing a type of ferroelectricity whose mechanism still remains to be understood. Thin films with increased crystal quality are therefore needed. We report the epitaxial growth of Hf0.5Zr0.5O2 thin films on (001)-oriented La0.7Sr0.3MnO3/SrTiO3 substrates. The films, which are under epitaxial compressive strain and predominantly (111)-oriented, display large ferroelectric polarization values up to 34 mu C cm(-2) and do not need wake-up cycling. Structural characterization reveals a rhombohedral phase, different from the commonly reported polar orthorhombic phase. This finding, in conjunction with density functional theory calculations, allows us to propose a compelling model for the formation of the ferroelectric phase. In addition, these results point towards thin films of simple oxides as a vastly unexplored class of nanoscale ferroelectrics.

Original languageEnglish
Pages (from-to)1095-1100
Number of pages7
JournalNature Materials
Volume17
Issue number12
Early online date22-Oct-2018
Publication statusPublished - Dec-2018

    Keywords

  • FIELD-CYCLING BEHAVIOR, CRYSTAL-STRUCTURE, DEPOLARIZATION-FIELD, ZIRCONIA, TRANSFORMATION, POLARIZATION, TRANSITION, SURFACES, ZRO2

ID: 66729220