On the Microscopic Origin of Negative Capacitance in Ferroelectric Materials: A Toy Model
On the Microscopic Origin of Negative Capacitance in Ferroelectric Materials: A Toy Model
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DOI：
10.1109/iedm.2018.8614574
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发表时间：
2018-12
期刊：
影响因子：
--
通讯作者：
A. Khan
中科院分区：
文献类型：
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作者：
A. Khan
我们对导致铁电材料中负现象出现的潜在微观机制提出了一个简单的物理解释。这里介绍的材料的灵感来自于费曼和基特尔对铁电性的教学处理。在一个由可极化单元(即晶体结构的原子或单元单元)的线性一维链组成的玩具模型中，我们展示了简单的静电相互作用如何产生微观的正反馈作用，从而导致负电容现象。我们指出，不稳定的负电容效应起源于所谓的“极化突变”现象，这是解释位移型铁电材料的关键。此外，通过玩具模型清楚地表明，即使在负电容状态下，单个偶极子也总是沿着局部电场的方向而不是相反的方向排列。最后，给出了在有序的极化单元集合中，“$S”形状的极化-外加电场曲线是如何从静电相互作用中出现的。
We present a simple, physical explanation of underlying microscopic mechanisms that lead to the emergence of the negative phenomena in ferroelectric materials. The material presented herein is inspired by the pedagogical treatment of ferroelectricity by Feynman and Kittel. In a toy model consisting of a linear one-dimensional chain of polarizable units (i.e., atoms or unit cells of a crystal structure), we show how simple electrostatic interactions can create a microscopic, positive feedback action that leads to negative capacitance phenomena. We point out that the unstable negative capacitance effect has its origin in the so called “polarization catastrophe” phenomenon which is essential to explain displacement type ferroelectrics. Furthermore, the fact that even in the negative capacitance state, the individual dipole always aligns along the direction of the local electrical field not opposite is made clear through the toy model. Finally, how the “$S$”-shaped polarization vs. applied electric field curve emerges out of the electrostatic interactions in an ordered set of polarizable units is shown.