| Autor: |
Shogo Tomoda, Takayuki Kitamura, Takahiro Shimada |
| Rok vydání: |
2011 |
| Předmět: |
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| Zdroj: |
Journal of physics. Condensed matter : an Institute of Physics journal. 22(35) |
| ISSN: |
1361-648X |
| Popis: |
We performed ab initio density functional theory calculations to investigate ferroelectricity at PbTiO(3) surface steps consisting of (100) and (001) surfaces with the polar axis in the [010] direction. Ferroelectricity was enhanced at PbO-terminated surface steps due to enhanced covalent Pb-O bonding because of the low coordination number of Pb atoms at the step edge. In contrast, ferroelectric distortions were suppressed at TiO(2)-terminations, because of electron transfer from Pb-O sites to Ti-O sites. Spontaneous polarization at the surface step increased when tensile strain was applied in the [010] direction and decreased when compressive strain was applied. At a critical compressive strain, the polarization direction changed and a polydomain structure was formed that consisted of 90° and 180° domain walls aligned with the surface step edge. This polydomain structure compensates surface charges that would generate a depolarizing field, thereby stabilizing ferroelectric distortions at the surface step. The polydomain structure also explains the formation mechanism of the experimentally observed 180° domain wall pinned at the surface step edge. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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