The shifting, scintillating pattern you can see when you stack two slightly misaligned window screens is called moiré. A similar interference effect occurs when scientists stack two-dimensional crystals with mismatched atomic spacings. Moiré superlattices display exotic physical properties that are absent in the layers that make up the patterns. These properties are rooted in the quantum nature of electrons.
Click here for original story, When material goes quantum, electrons slow down and form a crystal
Source: Phys.org