近日，荷兰拉德堡大学的A. Kirilyuk及其研究团队取得一项新进展。经过不懈努力，他们发现近零介电常数状态能够实现铁电极化的永久超快全光反转。相关研究成果已于2024年4月9日在国际知名学术期刊《自然—光子学》上发表。

该研究团队成功证明了在ENZ条件下，超快激发能够诱导铁电极化在不同稳定状态之间实现永久性的全光反转。研究人员深入探究了自然产生于固体离子晶格中的ENZ条件的影响，并发现所证实的反转机制具有真正的普遍性，能够在多种系统中实现序参数的永久开关功能。

据悉，强光-物质相互作用构成了所有光子应用的基石，赋予材料元素创造和调解光与光相互作用的能力。在寻找促进这种高效光-物质相互作用的新介质的过程中，一类有前途的材料出现了，它们具有非常不寻常的特性，因为它们的介电常数ε等于或至少非常接近于零。迄今为止的研究已经显示，近零介电常数（ENZ）状态下展现出的增强非线性光学效应，为构建超快瞬态光开关提供了可能。然而，一个尚未解决的关键问题是，是否能在ENZ条件下，通过放大光与物质之间的相互作用，实现永久性的开关功能。

附：英文原文

Title: Epsilon-near-zero regime enables permanent ultrafast all-optical reversal of ferroelectric polarization

Author: Kwaaitaal, M., Lourens, D. G., Davies, C. S., Kirilyuk, A.

Issue&Volume: 2024-04-09

Abstract: Strong light–matter interaction constitutes the bedrock of all photonic applications, empowering material elements with the ability to create and mediate interactions of light with light. Amidst the quest to identify new agents facilitating such efficient light–matter interactions, a class of promising materials has emerged, featuring highly unusual properties deriving from their dielectric constant ε being equal, or at least very close, to zero. Works so far have shown that the enhanced nonlinear optical effects displayed in this epsilon-near-zero (ENZ) regime make it possible to create ultrafast albeit transient optical switches. An outstanding question, however, relates to whether one could use the amplification of light–matter interactions at the ENZ conditions to achieve permanent switching. Here we demonstrate that an ultrafast excitation under ENZ conditions can induce permanent all-optical reversal of ferroelectric polarization between different stable states. Our reliance on ENZ conditions that naturally emerge from the solid’s ionic lattice suggests that the demonstrated mechanism of reversal is truly universal, being capable of permanently switching order parameters in a wide variety of systems.

DOI: 10.1038/s41566-024-01420-3

Source: https://www.nature.com/articles/s41566-024-01420-3