近日，英国曼彻斯特大学的Kostya S. Novoselov及其研究团队取得一项新进展。经过不懈努力，他们提出探索高各向异性范德华材料的几何和光学方法。相关研究成果已于2024年3月8日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队提出了一种基于范德华材料晶体几何角度和光学表征的简易研究方法。通过这种方法，他们发现As2S3是一种高度各向异性的范德华材料，其面内光学各向异性超过金红石20%，更是方解石的两倍之多。此外，As₂S₃具有高折射率，且在可见光范围内保持透明，成功打破了金红石长达一个世纪的光学记录。

鉴于这些显著优势，As₂S₃为下一代纳米光子学领域开辟了新的道路，这一点通过其作为超薄真正零阶四分之一波片的应用得到了验证，该波片融合了经典与法布里-帕姆罗光学相位积累技术。因此，这一研究方法不仅高效易行，更为寻找具有最大各向异性的范德华材料提供了新的思路。

据悉，范德华（vdW）材料的问世，极大推动了对其高光学、机械及电子各向异性特性的探索，从而为无数新现象与应用开辟了新的道路。这一重要突破进一步激发了科研界对范德华材料中更高各向异性特性的深入探索。然而，在庞大的范德华材料家族中筛选出最具潜力的材料，无疑是一项艰巨且富有挑战性的任务，需要创新的方法。

附：英文原文

Title: Exploring van der Waals materials with high anisotropy: geometrical and optical approaches

Author: Slavich, Aleksandr S., Ermolaev, Georgy A., Tatmyshevskiy, Mikhail K., Toksumakov, Adilet N., Matveeva, Olga G., Grudinin, Dmitriy V., Voronin, Kirill V., Mazitov, Arslan, Kravtsov, Konstantin V., Syuy, Alexander V., Tsymbarenko, Dmitry M., Mironov, Mikhail S., Novikov, Sergey M., Kruglov, Ivan, Ghazaryan, Davit A., Vyshnevyy, Andrey A., Arsenin, Aleksey V., Volkov, Valentyn S., Novoselov, Kostya S.

Issue&Volume: 2024-03-08

Abstract: The emergence of van der Waals (vdW) materials resulted in the discovery of their high optical, mechanical, and electronic anisotropic properties, immediately enabling countless novel phenomena and applications. Such success inspired an intensive search for the highest possible anisotropic properties among vdW materials. Furthermore, the identification of the most promising among the huge family of vdW materials is a challenging quest requiring innovative approaches. Here, we suggest an easy-to-use method for such a survey based on the crystallographic geometrical perspective of vdW materials followed by their optical characterization. Using our approach, we found As₂S₃ as a highly anisotropic vdW material. It demonstrates high in-plane optical anisotropy that is ~20% larger than for rutile and over two times as large as calcite, high refractive index, and transparency in the visible range, overcoming the century-long record set by rutile. Given these benefits, As₂S₃ opens a pathway towards next-generation nanophotonics as demonstrated by an ultrathin true zero-order quarter-wave plate that combines classical and the Fabry–Pérot optical phase accumulations. Hence, our approach provides an effective and easy-to-use method to find vdW materials with the utmost anisotropic properties.

DOI: 10.1038/s41377-024-01407-3

Source: https://www.nature.com/articles/s41377-024-01407-3