Non-volatile domain nucleation and growth in multiferroic BiFeO3 films.

We have presented a systematical study of the domain nucleation and growth behaviors in multiferroic BiFeO(3) (BFO) films. Both the ferroelectric and the ferroelastic switching dynamics were investigated. Several environmental parameters, including the polarization orientations, the monodomain-like matrix, and the ordered domain walls as local boundaries, were well controlled by thin-film strain engineering through changing the vicinal angles of the substrates.

Exploring topological defects in epitaxial BiFeO3 thin films.

Using a combination of piezoresponse force microscopy (PFM) and phase-field modeling, we demonstrate ubiquitous formation of center-type and possible ferroelectric closure domain arrangements during polarization switching near the ferroelastic domain walls in (100) oriented rhombohedral BiFeO(3). The formation of these topological defects is determined from the vertical and lateral PFM data and confirmed from the reversible changes in surface topography. These observations provide insight into the mechanisms of tip-induced ferroelastic domain control and suggest that formation of topological defect states under the action of local defect- and tip-induced fields is much more common than previously believed.