论文标题
层状波动融化铁电的
Lamellar fluctuations melt ferroelectricity
论文作者
论文摘要
我们考虑了铁电的标准金堡 - 兰道模型，其电偏振与弹性应变的梯度耦合。在谐波水平上，已知这种挠性相互作用可以杂交声音和光学声子模式，并导致具有调制的晶格结构的相位，该结构在对称性损坏状态之前，以实现足够大的耦合。在这里，我们使用我们使用自洽的声子近似来计算热和量子极化波动对裸模式的影响，以表明在所有温度下，这种长距离调制的顺序在所有温度下都是不稳定的。我们讨论对几乎铁电srtio $ _3 $和ktao $ _3 $的影响，并建议这些系统是基本调制状态的融化版本，该版本由非零动量热波动主导，除了最低的温度下。
We consider a standard Ginzburg-Landau model of a ferroelectric whose electrical polarization is coupled to gradients of elastic strain. At the harmonic level, such flexoelectric interaction is known to hybridize acoustic and optic phonon modes and lead to phases with modulated lattice structures that precede the symmetry broken state for sufficiently large couplings. Here, we use the we use the self-consistent phonon approximation to calculate the effects of thermal and quantum polarization fluctuations on the bare modes to show that such long-range modulated order is unstable at all temperatures. We discuss the implications for the nearly ferroelectric SrTiO$_3$ and KTaO$_3$, and propose that these systems are melted versions of an underlying modulated state which is dominated by non-zero momentum thermal fluctuations except at the very lowest temperatures.
