He-3 Crystals Viewed by a Fabry-Pérot Interferometer
Heikki Junes, LTT
In equilibrium, the surface of a crystal can be either smooth (faceted)
or rough (rounded) according to its crystallographic orientation and
temperature. The phase transition between these two surface states is
called roughening transition. With helium crystals purely interfacial
phenomena like faceting and growth kinetics, can be relatively easily
studied, compared with ordinary crystals.