Built-in surface field effect on the 180-degree domain wall structure in ferroics

We consider the influence of the built-in surface field on the 180-degree domain wall profile in primary ferroics within Landau-Ginsburg-Devonshire phenomenological approach. We predict the effect of domain wall bending near the surface caused by the built-in field and derived corresponding approximate analytical expressions. At that the higher is the surface energy contribution (i.e. the smaller is corresponding extrapolation length) and/or the higher is the field, the stronger is the bending effect. Built-in surface field is one of the possible mechanisms of domain wall near surface broadening recently observed in the ferroics.