Electrochemical ferroelectric switching: Origin of polarization reversal in ultrathin films
Electrochemical ferroelectric switching: Origin of polarization reversal in ultrathin films
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DOI：
10.1103/physrevb.85.024106
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发表时间：
2011-08
影响因子：
3.7
通讯作者：
N. Bristowe;M. Stengel;P. Littlewood;J. M. Pruneda;E. Artacho
中科院分区：
文献类型：
--
作者：
N. Bristowe;M. Stengel;P. Littlewood;J. M. Pruneda;E. Artacho
与预期相反，最近在暴露于空气中的纳米（1nm）铁电膜中观察到了鲁棒的可切换铁电性。Nature（伦敦）460，81（2009）]。基于第一性原理的计算，我们表明，系统不闪烁，除非带电缺陷或吸附物在表面形成。我们建议电化学过程作为最有可能的起源，这种电荷。薄膜的铁电极化与极化时氧化还原过程在其表面产生的外部离子电荷相适应。这反过来又改变了底部电极界面处的能带排列，解释了观察到的隧穿电阻。我们的结论是支持不同的电化学方案计算的能量。
Against expectations, robust switchable ferroelectricity has been recently observed in ultrathin (1 nm) ferroelectric films exposed to air V. Garcia et al., Nature (London) 460, 81 (2009)]. Based on first-principles calculations, we show that the system does not polarize unless charged defects or adsorbates form at the surface. We propose electrochemical processes as the most likely origin of this charge. The ferroelectric polarization of the film adapts to the external ionic charge generated on its surface by redox processes when poling the film. This, in turn, alters the band alignment at the bottom electrode interface, explaining the observed tunneling electroresistance. Our conclusions are supported by energetics calculated for varied electrochemical scenarios.