Interaction between free boundaries and domain walls in ferroelastics

We study the relaxation of ferroelastic domain walls in the vicinity of a free surface, by means of a nonlinear continuum elastic model treated with finite elements on an adaptive grid. Domain walls bend towards the free surface, as a consequence of the interplay of the energy per unit length of the domain wall and the long-range elastic strains which are generated by deviations from the prescribed compatible orientation. We also analyze the order parameter on the free surface. For walls orthogonal to the free surface we find, in accordance with previous studies, a double-peak structure. For different angles the picture is more complex, and in some cases only one small peak survives.