Natural 2D layered mineral cannizzarite with anisotropic optical responses

Abstract

Cannizzarite is a naturally occurring mineral formed by van der Waals (vdW) stacking of alternating layers of PbS-like and Bi2S3-like two-dimensional (2D) materials. Although the PbS-type and Bi2S3-type 2D material layers are structurally isotropic individually, the forced commensuration between these two types of layers while forming the heterostructure of cannizzarite induces strong structural anisotropy. Here we demonstrate the mechanical exfoliation of natural cannizzarite mineral to obtain thin vdW heterostructures of PbS-type and Bi2S3-type atomic layers. The structural anisotropy induced anisotropic optical properties of thin cannizzarite flakes are explored through angle-resolved polarized Raman scattering, linear dichroism, and polarization-dependent anisotropic third-harmonic generation. Our study establishes cannizzarite as a new natural vdW heterostructure-based 2D material with highly anisotropic optical properties for realizing polarization-sensitive linear and nonlinear photonic devices for future on-chip optical computing and optical information processing.

Large in-plane vibrational and optical anisotropy in natural 2D heterostructure abramovite

“…In addition, a slight amount of Se is found to be present in the crystal. The presence of a small amount of Se has previously been observed in other sulfosalts 32 . The signal of Cu is present owing to the copper TEM grid.…”

“…These rippling fringes are recognized as interlayer moiré patterns in vdW heterostructures, which are ascribable to the crystal lattice deformation under the periodic strain during the forced commensuration between the incommensurate constituent Q- and H-layers. In previous studies, such rippling fringes have been noticed in other natural vdW heterostructures of sulfosalts including cylindrite 28 , franckeite 22 , 40 , lengenbachite 31 , and cannizzarite 32 . The atomic arrangement of the constituent lattices at the crystal surface is shown in the high-resolution (HR) TEM image in Fig.…”

“…Hence, angle-resolved polarized Raman spectroscopy studies can unveil the in-plane structural anisotropy in the triclinic crystal of abramovite by analyzing the anisotropic phonon vibrational modes. This method has previously been used for determining the crystal anisotropy in other sulfosalt minerals such as cylindrite 28 , frankeite 40 , lengenbachite 31 , cannizzarite 32 , and nagyágite 55 . Figure 3 b shows the contour color map of the variation of Raman intensity for the parallel polarization components of the Raman modes within the range of 65 to 600 cm -1 as a function of the incident linear polarization angle , where for the polarization along the x -axis as labeled in Fig.…”

“…Structural anisotropy in a vdW heterostructure induces linear dichroism. Previously, polarization-dependent absorption measurements have been used to probe the linear dichroism and the crystal axes of other natural anisotropic vdW heterostructures such as cylindrite 28 , franckeite 40 , lengenbachite 31 , cannizzarite 32 , and nagyágite 55 . With that hindsight, next we investigate the evolution of the absorbance in abramovite crystal depending on the incident light polarization for the same 26 nm-thick flake.…”

“…Previously, the mechanical exfoliation of several members of this sulfosalt family has been demonstrated to produce ultrathin layers of vdW heterostructures. For example, cylindrite 28 , 29 and franckeite 22 , 30 have been studied for the formation of vdW heterostructures with constituent PbS-type and SnS 2 -type layers, while lengenbachite 31 and cannizzarite 32 have been exfoliated for creating vdW heterostructures with alternatively stacked PbS-type layer and As 2 S 3 - or Bi 2 S 3 -type layer. It has been observed that these resultant vdW heterostructures exhibit in-plane structural anisotropy caused by the lattice deformation between the incommensurate constituent isotropic 2D material layers.…”