Traveling-wave states in deep-groove directional solidification

We observe asymmetric cells with deep grooves in directional solidification of a nearly pure material. These cells propagate laterally in a direction determined by the sign of their asymmetry. Measurements of their phase speed and asymmetry agree qualitatively with current theories. We observe spatiotemporal dislocations and identify them with either lateral boundaries or crystal grain boundaries. At higher solidification speeds, we also observe periodic shape oscillations coherent over many cells.