Symmetry Breakdown in Franckeite: Spontaneous Strain, Rippling, and Interlayer Moire: Spontaneous Strain, Rippling, and Interlayer Moiré

Franckeite is a naturally occurring layered mineral with a structure composed of alternating stacks of SnS2-like and PbS-like layers. Although this superlattice is composed of a sequence of isotropic two-dimensional layers, it exhibits a spontaneous rippling that makes the material structurally anisotropic. We demonstrate that this rippling...