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

作者：Wei, Yingfen; Nukala, Pavan; Salverda, Mart; Matzen, Sylvia; Zhao, Hong Jian; Momand, Jamo; Everhardt, Arnoud S.; Agnus, Guillaume; Blake, Graeme R.; Lecoeur, Philippe; Kooi, Bart J.; Iniguez, Jorge; Dkhil, Brahim; Noheda, Beatriz^*

来源：Nature Materials, 2018, 17(12): 1095-+.

DOI：10.1038/s41563-018-0196-0

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

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.

• 出版日期2018-12