Equilibrium Polarization of Ultrathin PbTiO3 with Surface Compensation Controlled by Oxygen Partial Pressure
Equilibrium Polarization of Ultrathin PbTiO3 with Surface Compensation Controlled by Oxygen Partial Pressure
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DOI：
10.1103/physrevlett.107.187602
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发表时间：
2011-10-25
影响因子：
8.6
通讯作者：
Stephenson, G. B.
中科院分区：
文献类型：
--
作者：
Highland, M. J.;Fister, T. T.;Stephenson, G. B.
我们提出了一个同步辐射X射线研究的平衡极化结构的SrRuO 3电极上的SrTiO 3（001）衬底上外延生长的PbTiO 3薄膜，作为一个函数的温度和外部氧分压（PO（2））控制其表面电荷补偿。我们发现铁电居里温度（T-C）随pO（2）的变化而变化，在pO（2）的中间值处有一个极小值，低于T-C的极化改变了符号。实验是在定性协议与模型的基础上，考虑到相互作用的相变与带电表面物种的电化学平衡的朗道理论。当表面物种的浓度不足以补偿任一极性取向时，顺电相稳定在中间pO（2）。
We present a synchrotron x-ray study of the equilibrium polarization structure of ultrathin PbTiO3 films on SrRuO3 electrodes epitaxially grown on SrTiO3 (001) substrates, as a function of temperature and the external oxygen partial pressure (pO(2)) controlling their surface charge compensation. We find that the ferroelectric Curie temperature (T-C) varies with pO(2) and has a minimum at the intermediate pO(2), where the polarization below T-C changes sign. The experiments are in qualitative agreement with a model based on Landau theory that takes into account the interaction of the phase transition with the electrochemical equilibria for charged surface species. The paraelectric phase is stabilized at intermediate pO(2) when the concentrations of surface species are insufficient to compensate either polar orientation.