Quasiperiodic Bloch-like states in a surface-wave experiment.

Bloch-like surface waves associated with a quasiperiodic structure are observed in a classic wave propagation experiment which consists of pulse propagation with a shallow fluid covering a quasiperiodically drilled bottom. We show that a transversal pulse propagates as a plane wave with quasiperiodic modulation, displaying the characteristic undulatory propagation in this quasiperiodic system and reinforcing the idea that analogous concepts to Bloch functions can be applied to quasicrystals under certain circumstances.

Moiré patterns in high resolution electron microscopy images of MoS2.

The contrast observed in the (0001) HREM images of MoS2 are interpreted with a model based on rotational moiré patterns. Computer-simulated images show that rotations of two supercells by angles of 3, 5, 8, and 16 degrees around their centers reproduce the contrast observed in the experimental images. The calculations suggest that these rotations occur between the sulphur layers of the MoS2 structure.