Phase transitions in typical fluorite-type ferroelectrics
| Autor: | Yu, Heng, Xue, Kan-Hao, Feng, Nan, Zheng, Yunzhe, Cheng, Yan, Xu, Ben, Miao, Xiangshui |
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| Rok vydání: | 2024 |
| Předmět: | |
| Zdroj: | Applied Physics Letters 125, 102903 (2024) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1063/5.0224576 |
| Popis: | While ferroelectric hafnia ($\mathrm{HfO_2}$) has become a technically important material for microelectronics, the physical origin of its ferroelectricity remains poorly understood. The tetragonal $P4_2/nmc$ phase is commonly assigned as its paraelectric mother phase but has no soft mode at the Brillouin zone center. In this work, we propose that the paraelectric-ferroelectric transition in hafnia-like $Pca2_1$ ferroelectric family can be described by a $Pcca$-$Pca2_1$ transition, where the $Pcca$ mother phase will evolve into either the $Pca2_1$ ferroelectric phase or the centrosymmetric $P2_1/c$ monoclinic phase, depending on the strain conditions. The $Pcca$ phase is directly linked to both phases in the context of continuous phase transition. Hafnia is regarded as a special case of this family, in that it has accidental atomic degeneracy because all anions are oxygen. The theory is also correlated to the seven-coordination theory that explains the ferroelectricity in hafnia from a chemical perspective. In addition, the strain conditions to promote the ferroelectric phase in hafnia are discussed. Comment: 12 pages, 4 figures |
| Databáze: | arXiv |
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