SrTiO_3缓冲层引起的铁电薄膜极化对称性破缺

Broken Inversion Symmetry in Ferroelectric Thin Film Induced by SrTiO_3 Buffer Layer

采用第一性原理方法从原子尺度研究了SrTiO_3缓冲层对Pt/PbTiO_3/Pt铁电电容的极化强度和稳定性的影响。针对PbO和TiO_2 2种不同终端表面的PbTiO_3铁电电容,在Pt与PbTiO_3的下界面处逐层引入SrTiO_3缓冲层,研究了PbTiO_3薄膜极化性质的演化规律。结果表明,引入SrTiO_3缓冲层会不同程度地破坏PbTiO_3薄膜的极化对称性,使指向上表面的极化状态更为稳定,这对于要求双稳极化状态的铁电存储器是不利的。

The influence of SrTiO3 buffer layer on the polarization and stability of Pt/ PbTiO3/Pt capacitor was investigated based on first-principles calculation. Taking account of the PbO or TiO2-terminated PbTiO3 ferroelectrie capacitors, the polarization properties of PbTiO3 ferroeleetric capacitors were studied when SrTiO3 layers were inset at the bottom in- terface between Pt and PbTiO3. The results indicate that the polarization symmetry of PbTiO3 thin films can be destroyed to some extent by introducing SrTiO3 buffer layer, and polarization directing upward is more stabilized, which is bad for the ferroelectric memory of bistable polarization state.