Dasgupta Arindam, Belakovskiy Dmitriy I, Chaplygin Ilya V, Gao Jie, Yang Xiaodong
Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO, 65409, USA.
Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia, 119071.
Sci Rep. 2022 Oct 7;12(1):16803. doi: 10.1038/s41598-022-21042-5.
The design and formation of van der Waals (vdW) heterostructures with different two-dimensional (2D) materials provide an opportunity to create materials with extraordinary physical properties tailored toward specific applications. Mechanical exfoliation of natural vdW materials has been recognized as an effective way for producing high-quality ultrathin vdW heterostructures. Abramovite is one of such naturally occurring vdW materials, where the superlattice is composed of alternating PbBiS and SnInS 2D material lattices. The forced commensuration between the two incommensurate constituent 2D material lattices induces in-plane structural anisotropy in the formed vdW heterostructure of abramovite, even though the individual 2D material lattices are isotropic in nature. Here, we show that ultrathin layers of vdW heterostructures of abramovite can be achieved by mechanical exfoliation of the natural mineral. Furthermore, the structural anisotropy induced highly anisotropic vibrational and optical responses of abramovite thin flakes are demonstrated by angle-resolved polarized Raman scattering, linear dichroism, and polarization-dependent third-harmonic generation. Our results not only establish abramovite as a promising natural vdW material with tailored linear and nonlinear optical properties for building future anisotropic integrated photonic devices, but also provide a deeper understanding of the origin of structural, vibrational and optical anisotropy in vdW heterostructures.
具有不同二维材料的范德华（vdW）异质结构的设计与形成，为制造具有针对特定应用定制的非凡物理特性的材料提供了契机。天然vdW材料的机械剥离已被公认为是生产高质量超薄vdW异质结构的有效方法。钙铋锡矿就是这样一种天然存在的vdW材料，其超晶格由交替的PbBiS和SnInS二维材料晶格组成。尽管单个二维材料晶格本质上是各向同性的，但两种不相称的组成二维材料晶格之间的强制相称会在形成的钙铋锡矿vdW异质结构中诱导面内结构各向异性。在此，我们表明通过对天然矿物进行机械剥离可以获得钙铋锡矿vdW异质结构的超薄层。此外，通过角分辨偏振拉曼散射、线性二向色性和偏振相关的三次谐波产生，证明了钙铋锡矿薄片的结构各向异性诱导出高度各向异性的振动和光学响应。我们的结果不仅确立了钙铋锡矿作为一种有前景的天然vdW材料，具有为构建未来各向异性集成光子器件量身定制的线性和非线性光学特性，而且还提供了对vdW异质结构中结构、振动和光学各向异性起源的更深入理解。
