Lengenbachite is a naturally occurring layered mineral formed with alternating stacks of two constituent PbS-like and M2S3-like two-dimensional (2D) material layers due to the phase segregation process during the formation. Here, we demonstrate to achieve van der Waals (vdW) heterostructures of lengenbachite down to a few layer-pair thickness by mechanical exfoliation of bulk lengenbachite mineral. The incommensurability between the constituent isotropic 2D material layers makes the formed vdW heterostructure exhibit strong in-plane structural anisotropy, which leads to highly anisotropic optical responses in lengenbachite thin flakes, including anisotropic Raman scattering, linear dichroism, and anisotropic third-harmonic generation. Moreover, we exploit the nonlinear optical anisotropy for polarization-dependent intensity modulation of the converted third-harmonic optical vortices. Our study establishes lengenbachite as a new natural vdW heterostructure-based 2D material with unique optical properties for realizing anisotropic optical devices for photonic integrated circuits and optical information processing.
A. Dasgupta et al., "Naturally Occurring Van Der Waals Heterostructure Lengenbachite with Strong In-Plane Structural and Optical Anisotropy," npj 2D Materials and Applications, vol. 5, no. 1, article no. 88, Nature Research, Nov 2021.
The definitive version is available at https://doi.org/10.1038/s41699-021-00271-8
Mechanical and Aerospace Engineering
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29 Nov 2021