Spontaneous interlayer compression in commensurately stacked van der Waals heterostructures

Stacks of nanostructured 2D materials can display properties distinct from those of the parent materials. In heterostructures of transition metal dichalcogenides, the authors find here that dissimilar chalcogen species induce a spontaneous compression of the van der Waals gap. This compression is a result of the induced charge displacement within and between the layers, which modifies the out-of-plane polarizability, and can stabilize charge density waves or induce ferroelectricity. The authors hope to stimulate experimental investigation of tunability in mixed chalcogen systems.