The roughening transition of crystal surfaces. II. experiments on static and dynamic properties near the first roughening transition of hcp 4He

We summarize in this paper our present experimental knowledge about the roughening transition of (0001) interfaces of hcp 4He crystals, at TR = 1.28 K. We describe in detail new and precise measurements of their growth rate, obtained by an interferometric method. They show a broadening of the transition due to non-equilibrium conditions. These new results, together with step energy and surface stiffness measurements, are analysed in the light of the recent developments of the theory of roughening, exposed in the preceeding paper. The agreement is quantitative, and proves that it is a smooth, infinite order transition, of the Kosterlitz-Thouless type.