  While measurements of the polar dependence of the surface free energy are
easily available, measurements of the whole polar dependence of the surface
stress of a crystal do not exist. In this paper is presented a new procedure
that allows, for the first time, the experimental determination of the surface
stress polar dependence of a crystal. For this purpose (1) electromigration is
used to control the kinetic faceting of surface orientations that belong to the
equilibrium shape of the crystal and (2) for each destabilised surface, the
period of faceting as well as the crystallographic angles of the appearing
facets are measured by AFM. The so-obtained data lead to a set of equations
whose mathematical solution, compatible with physical constraints, gives access
to the surface stress polar dependence of the whole crystal and thus to a
better understanding of surface stress properties.
