Indirect but Efficient: Laser-Excited Electrons Can Drive Ultrafast Polarization Switching in Ferroelectric Materials,The Journal of Physical Chemistry Letters

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Indirect but Efficient: Laser-Excited Electrons Can Drive Ultrafast Polarization Switching in Ferroelectric Materials
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2019-06-07 00:00:00 , DOI: 10.1021/acs.jpclett.9b01046
Chao Lian ₁ , Zulfikhar A. Ali ₁ , Hyuna Kwon ₁ , Bryan M. Wong ₁

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To enhance the efficiency of next-generation ferroelectric (FE) electronic devices, new techniques for controlling ferroelectric polarization switching are required. While most prior studies have attempted to induce polarization switching via the excitation of phonons, these experimental techniques required intricate and expensive terahertz sources and have not been completely successful. Here, we propose a new mechanism for rapidly and efficiently switching the FE polarization via laser-tuning of the underlying dynamical potential energy surface. Using time-dependent density functional calculations, we observe an ultrafast switching of the FE polarization in BaTiO₃ within 200 fs. A laser pulse can induce a charge density redistribution that reduces the original FE charge order. This excitation results in both desirable and highly directional ionic forces that are always opposite to the original FE displacements. Our new mechanism enables the reversible switching of the FE polarization with optical pulses that can be produced from existing 800 nm experimental laser sources.

中文翻译：

间接但高效：激光激发的电子可以驱动铁电材料中的超快偏振转换

为了提高下一代铁电（FE）电子设备的效率，需要用于控制铁电极化切换的新技术。尽管大多数先前的研究尝试通过声子的激发来诱导极化转换，但是这些实验技术需要复杂且昂贵的太赫兹源，并且尚未完全成功。在这里，我们提出了一种新的机制，可以通过对潜在的动态势能面进行激光调谐来快速有效地切换FE偏振。使用随时间变化的密度泛函计算，我们观察到BaTiO _3中FE极化的超快速切换在200 fs之内激光脉冲会引起电荷密度重新分布，从而降低原始的FE电荷阶数。这种激发会产生理想的和高度定向的离子力，这些力始终与原始的FE位移相反。我们的新机制可通过可从现有800 nm实验激光源产生的光脉冲来实现FE偏振的可逆切换。

更新日期：2019-06-07

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