Phase field model for composite stepped surface

We present a phase field model for the evolution of stepped surfaces with distinct material parameters across nanoscale terraces in surface diffusion. The model aims to capture the Burton-CabreraFrank (BCF)-type theory for the motion of decorated non-interacting steps separating composite terraces. Our work forms an extension of the phase field model by Hu et al. [Physica D 241, 77 (2012)]. The transport processes are diffusion of adsorbed atoms (adatoms) on terraces and along step edges, and attachment-detachment of atoms at steps, enriched with sequences of distinct kinetic rates. Material deposition from above, desorption and Ehrlich-Schwoebel barriers are included. We discuss how the phase field model reduces to the (sharp-interface) BCF-type theory.