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arXiv 0908.1813cond-mat.mtrl-sci
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铁电电容器的第一性原理约束D计算模型

First-principles modeling of ferroelectric capacitors via constrained-D calculations

Massimiliano Stengel, David Vanderbilt, Nicola A. Spaldin

备注：
25 pages, 18 figures
发表信息：
Phys. Rev. B 80, 224110 (2009)
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摘要：

由于金属电极、长程静电力和短程界面化学的共存，铁电电容器的第一性原理建模提出了几个技术挑战。在这里，我们将展示如何使用有限场密度泛函理论形式主义，其中的基本电变量是位移场D，这些方面可以有效地和准确地合理化。通过对模型Pt/BaTiO 3/Pt和Au/BaZrO 3/Au电容器进行计算，我们演示了如何识别和严格分离界面特定和块特定的属性。然后，我们展示了如何任意厚度和几何形状（对称或不对称）的电容器的电性能可以很容易地重建使用这样的信息。最后，我们将展示如何有用的观测值，如极化和介电，压电和电致伸缩系数很容易评估作为上述过程的副产品。我们应用这种方法来阐明简单的金属/氧化物界面的化学键合，肖特基势垒和铁电极化之间的关系。我们发现，BO 2电极界面的行为类似于一层线性电介质与块状钙钛矿薄膜串联，而在AO电极界面发生显着的非线性效应。

英文摘要：

First-principles modeling of ferroelectric capacitors presents several technical challenges, due to the coexistence of metallic electrodes, long-range electrostatic forces and short-range interface chemistry. Here we show how these aspects can be efficiently and accurately rationalized by using a finite-field density-functional theory formalism in which the fundamental electrical variable is the displacement field D. By performing calculations on model Pt/BaTiO3/Pt and Au/BaZrO3/Au capacitors we demonstrate how the interface-specific and bulk-specific properties can be identified and rigorously separated. Then, we show how the electrical properties of capacitors of arbitrary thickness and geometry (symmetric or asymmetric) can be readily reconstructed by using such information. Finally, we show how useful observables such as polarization and dielectric, piezoelectric and electrostrictive coefficients are easily evaluated as a byproduct of the above procedure. We apply this methodology to elucidate the relationship between chemical bonding, Schottky barriers and ferroelectric polarization at simple-metal/oxide interfaces. We find that BO2-electrode interfaces behave analogously to a layer of linear dielectric put in series with a bulk-like perovskite film, while a significant non-linear effect occurs at AO-electrode interfaces.

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