论文标题
在PBTIO $ _ {3} $的超级晶格中控制铁电磁滞偏移
Controlling ferroelectric hysteresis offsets in PbTiO$_{3}$ based superlattices
论文作者
论文摘要
铁电材料的特征是具有多个极化方向的退化基态。在铁电容器中，这应该表现为同样有利的上下极化状态。但是，这种理想的行为很少在铁电薄膜和超晶格设备中观察到，这些薄膜和超晶格设备通常表现出内置的偏见，偏离一个极化状态而不是另一个极化状态。通常，这种极化不对称性可以归因于电极。在这项研究中，我们检查了PBTIO $ _3 $的铁电超晶格的偏见，而不是由于电极的原因，而是由于生长过程中接口形成的缺陷的性质。使用实验和第一原理模拟的组合，我们能够解释观察到的内置偏见及其与组成的进化的迹象。我们的见解使我们能够通过控制超晶格的组成和周期性来设计具有零置偏置的设备。
Ferroelectric materials are characterized by degenerate ground states with multiple polarization directions. In a ferroelectric capacitor this should manifest as equally favourable up and down polarization states. However, this ideal behavior is rarely observed in ferroelectric thin films and superlattice devices, which generally exhibit a built-in bias which favors one polarization state over the other. Often this polarization asymmetry can be attributed to the electrodes. In this study we examine bias in PbTiO$_3$-based ferroelectric superlattices that is not due to the electrodes, but rather to the nature of the defects that form at the interfaces during growth. Using a combination of experiments and first-principles simulations, we are able to explain the sign of the observed built-in bias and its evolution with composition. Our insights allow us to design devices with zero built-in bias by controlling the composition and periodicity of the superlattices.
