Scaling of superdomain bands in ferroelectric dots
Scaling of superdomain bands in ferroelectric dots
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DOI：
10.1063/1.3571560
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发表时间：
2011-03-28
影响因子：
4
通讯作者：
Gregg, J. M.
中科院分区：
文献类型：
--
作者：
McGilly, L. J.;Gregg, J. M.
在介观尺度的BaTiO_3单晶点中，观察到90度条纹域的束状物形成不同的群或带。矢量压电响应力显微镜(PFM)显示，当被认为是单个实体时，每个带区都具有大致沿<；110&>(伪立方体)方向的可分辨极化；这种产生的极化在相邻带中的反平行排列意味着这些区域可以被认为是180度的“超域”。对于侧壁尺寸小于2微米的点，观察到这些超畴宽度的Landau-Kittel状标度，强烈地表明它们的形成是对横向去极化场的响应。在较大的点结构中，比例律失效。我们通过考虑Landau-Kittel自由能模型所暗示的采用平衡超域周期的驱动力的变化，使这些观察结果合理化；我们得出结论，超域有序带的形成是一种独特的介观/纳米尺度现象。我们还注意到，PFM成像在空气中发现的超域带与Schling等人之前看到的象限排列形成了对比。[Nano Lett.，9,3359(2009)]通过真空中的透射电子显微镜成像。因此，边界条件的确切性质在确定纳米结构中自发形成的区域图案方面的重要性显然是隐含的。(C)2011年美国物理研究所。[DOI：10.1063/1.3571560]
Bundles of 90 degrees stripe domains have been observed to form into distinct groups, or bands, in mesoscale BaTiO3 single crystal dots. Vector piezoresponse force microscopy (PFM) shows that each band region, when considered as a single entity, possesses a resolved polarization that lies approximately along the < 110 >(pseudocubic) direction; antiparallel alignment of this resultant polarization in adjacent bands means that these regions can be considered as 180 degrees "superdomains." For dots with sidewall dimensions below similar to 2 mu m, Landau-Kittel like scaling in the width of these superdomains was observed, strongly suggesting that they form in response to lateral depolarizing fields. In larger dot structures, scaling laws break down. We have rationalized these observations by considering changes in the driving force for the adoption of equilibrium superdomain periodicities implied by Landau-Kittel-free energy models; we conclude that the formation of ordered bands of superdomains is a uniquely meso/nanoscale phenomenon. We also note that the superdomain bands found by PFM imaging in air contrast with the quadrant arrangements seen previously by Schilling et al. [Nano Lett., 9, 3359 (2009)] through transmission electron microscopy imaging in vacuum. The importance of the exact nature of the boundary conditions in determining the domain patterns that spontaneously form in nanostructures is therefore clearly implied. (C) 2011 American Institute of Physics. [doi:10.1063/1.3571560]