Influence of crystallographic steps on properties of ferroelectric ultrathin films: An ab initio study

A first-principles-based approach is used to investigate the effect of a crystallographic step on the existence and morphology of the recently discovered periodic nanostripe domains [S. K. Streiffer et al., Phys. Rev. Lett. 89, 067601 (2002)] in Pb(Zr1−xTix)O3 ultrathin films. It is found that these domain structures do not vanish in the presence of such defect but rather evolve to form original stripe configurations to accommodate this step. The morphology and energetics of these original configurations are provided. Their dependencies on the film’s thickness and the step’s height is also discussed.