Ferroelectric domains in multiferroic BiFeO3 films under epitaxial strains.
Ferroelectric domains in multiferroic BiFeO3 films under epitaxial strains.
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DOI：
10.1103/physrevlett.110.187601
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发表时间：
2013-05
影响因子：
8.6
通讯作者：
W. Ren;Yurong Yang;O. Diéguez;J. Íñiguez;N. Choudhury;L. Bellaiche
中科院分区：
文献类型：
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作者：
W. Ren;Yurong Yang;O. Diéguez;J. Íñiguez;N. Choudhury;L. Bellaiche
采用第一性原理计算来研究受压缩应变的BiFeO₃（BFO）薄膜中铁电畴壁（DWs）的能量和原子特性。对于小应变，发现畴壁能显著低于先前报道的值，并且不同类型畴壁之间的能量层级也不同。在所有研究的情况中（对应于畴极化形成的理想角度为71°、109°和180°），当失配应变处于单畴BFO中R相和T相转变的临界应变附近时，畴壁能达到最大值。在这些应变附近，一些量强烈依赖于畴壁的类型；这种独特的行为与180°情况下畴壁处的弹性差异和较大的面外极化有关。应变大小的进一步增加导致（i）畴壁能层级的改变，（ii）每个上下畴内部较大的面外极化，以及（iii）畴壁处新的原子排列。因此，我们的研究可以开启一个新的研究方向，即畴壁功能的应变工程。
First-principles calculations are performed to investigate energetic and atomistic characteristics of ferroelectric domains walls (DWs) of BiFeO(3) (BFO) films subject to compressive strain. Significantly lower DW energies than those previously reported, and a different energetic hierarchy between the various DW types, are found for small strains. In all investigated cases (corresponding to ideal angles of 71°, 109°, and 180° formed by the domain polarizations), the DW energy reaches its maximum value for misfit strains that are around the critical strain at which the transition between the R-like and T-like phases occurs in single-domain BFO. Near these strains, several quantities depend strongly on the type of domain wall; such distinct behavior is associated with an elastic difference and a large out-of-plane polarization at the DW in the 180° case. A further increase of the magnitude of the strain leads to (i) a change of hierarchy of the DW energies, (ii) large out-of-plane polarizations inside each up and down domain, and (iii) novel atomic arrangements at the domain walls. Our study can thus initiate a new research direction, namely strain engineering of domain-wall functionalities.