Key Laboratory of Inorganic Functional Material and Device, CAS Shanghai Institute of Ceramics, Chinese Academy of Sciences
A new type of ferroelectric material - doped HfO2
Speaker: Yingfen Wei (魏莹芬)
Zernike Institute for Advanced Materials
University of Groningen，Holland
The ferroelectricity recently observed in ultra-thin films of doped-hafnia is robust at the nanoscale, where the other ferroelectrics loose their functionality. Hafnia is also Si-compatible, so this recent discovery represents a breakthrough in the field. However, the origin of this ferroelectricity remains elusive due to the extremely low thickness of the films and the presence of secondary phases, which hamper the characterization. In this work, epitaxial single-phase Hf0.5Zr0.5O2 films have been grown on La0.7Sr0.3MnO3/SrTiO3 substrates, displaying outstanding ferroelectric properties and superb crystallinity. Synchrotron x-ray diffraction and electron microscopy reveal a new polar rhombohedral phase, different from the commonly reported polar orthorhombic phase. Aided by density functional theory, we propose a compelling model for the stabilization of FE phase and provide guidelines to uncover ferroelectricity in other simple oxides1.
 Y. Wei et al. Nature Materials 17, 1095 (2018)