Facet destabilization and macrostep dynamics at the smectic-A smectic-B interface

We describe the behavior m directional solidification of the faceted smectic-A smectic-B interface of 408 (butyloxybenzihdene octylaniline) Above the onset of instability, which is given by the classical constitutional-supercooling cntenon, we observe the nucleation of macrosteps Several mechanisms are possible, depending on the velocity These macrosteps are always unstable and propagate along the macroscopic interface, changing shape continuously. We