Second gradient vs. surface energy in the Asaro-Grinfeld instability

This paper study an instability phenomenon that arise in epitaxial growth o f single crystals with lattice mismatch. We compare a classical approach, b ased on the competition between the bulk and surface energies, with a non-s tandard one when the surface term is replaced by a term including the secon d gradient of the displacement field. We evidence how second order gradient s may stabilize lower modes of corrugated boundaries, via an intrinsic leng th scale.