Uniaxial strain-induced ferroelectric phase with a giant axial ratio in a (110) BiFeO3 thin film
Uniaxial strain-induced ferroelectric phase with a giant axial ratio in a (110) BiFeO3 thin film
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DOI：
10.1103/physrevb.87.220101
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发表时间：
2013-06-06
影响因子：
3.7
通讯作者：
Wang, John
中科院分区：
文献类型：
--
作者：
Liu, Huajun;Yang, Ping;Wang, John
应变工程是利用双轴错配应变来改变晶体结构的一种方法，是调整外延薄膜物理行为的有力工具。在这里，我们表明，10 nm厚的BiFeO 3薄膜是单轴应变（110）取向的LaAlO 3衬底，表现出一个巨大的c/a类似于1.24的单斜晶格和独特的条纹铁电畴配置，揭示了高分辨率同步辐射X射线衍射和压电力显微镜。通过第一性原理计算，预测了BiFeO_3在单轴应变条件下的应变-相图，表明在（110）取向的LaAlO_3衬底上应变时，具有130 μ C/cm（2）大极化率的单斜Pm相是能量最低的相。我们的结果提供了一个潜在的途径来调整外延铁电薄膜的物理行为，在（110）取向的单轴应变，而不是广泛研究的双轴应变（001）取向。
Strain engineering, which employs biaxial misfit strain to deform the crystal structure, is a powerful tool to tune the physical behavior of epitaxial thin films. Here we show that a 10-nm-thick BiFeO3 film is uniaxially strained by (110)-oriented LaAlO3 substrate, which exhibits a monoclinic lattice with a giant c/a similar to 1.24 and a unique stripe ferroelectric domain configuration, as revealed by high resolution synchrotron x-ray diffraction and piezoelectric force microscopy. A strain-phase diagram for BiFeO3 under uniaxial strain condition is predicted by first-principles calculations, suggesting that monoclinic Pm phase with a large polarization of similar to 130 mu C/cm(2) is the lowest-in-energy phase when strained by (110)-oriented LaAlO3 substrate. Our results provide a potential route to tune physical behavior of epitaxial ferroelectric thin films by uniaxial strain in (110) orientation, instead of widely investigated biaxial strain in (001) orientation.