Ideal barriers to polarization reversal and domain-wall motion in strained ferroelectric thin films
Ideal barriers to polarization reversal and domain-wall motion in strained ferroelectric thin films
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DOI：
10.1103/physrevb.79.144124
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发表时间：
2008-12
影响因子：
3.7
通讯作者：
S. Beckman;Xinjie Wang;K. Rabe;D. Vanderbilt
中科院分区：
文献类型：
--
作者：
S. Beckman;Xinjie Wang;K. Rabe;D. Vanderbilt
采用第一性原理计算方法研究了c相PbTiO_3（PTO）、PbZrO_3（PZO）和PbZr_{1-x}Ti_xO_3（PZT）中畴反转的理想本征势垒。研究了外延应变对原子结构、铁电响应、相干畴反转势垒、畴壁能量和畴壁平移势垒的影响。结果表明，PTO比PZO具有更大的极化，但畴反转能垒更小。因此，PTO中的理想矫顽场比PZO小两倍以上。Ti-O键长比晶体中的其它键长对应变更敏感。这导致PTO中的极化和畴壁能量比PZO中对应变具有更大的敏感性。研究了PZT的两种有序相：岩盐结构和（100）PTO/PZO超晶格。在这些简单的结构中，我们发现铁电性质不服从Vergard定律，而是可以近似为单个5原子晶胞的平均值。
The ideal intrinsic barriers to domain switching in c-phase PbTiO_3 (PTO), PbZrO_3 (PZO), and PbZr_{1-x}Ti_xO_3 (PZT) are investigated via first-principles computational methods. The effects of epitaxial strain on the atomic structure, ferroelectric response, barrier to coherent domain reversal, domain-wall energy, and barrier to domain-wall translation are studied. It is found that PTO has a larger polarization, but smaller energy barrier to domain reversal, than PZO. Consequentially the idealized coercive field is over two times smaller in PTO than PZO. The Ti--O bond length is more sensitive to strain than the other bonds in the crystals. This results in the polarization and domain-wall energy in PTO having greater sensitivity to strain than in PZO. Two ordered phases of PZT are considered, the rock-salt structure and a (100) PTO/PZO superlattice. In these simple structures we find that the ferroelectric properties do not obey Vergard's law, but instead can be approximated as an average over individual 5-atom unit cells.