Can interface dislocations degrade ferroelectric properties?

A thermodynamic analysis has been carried out to investigate the role of dislocations in ferroelectric materials. Due to the coupling of the stress field of the dislocation and the polarization, there is a drastic variation in the polarization near the dislocation. These polarization gradients result in strong depolarizing fields that suppress the polarization in a region that extends over several nanometrers. In epitaxial ferroelectric films, these polarization gradients should result in the formation of dead layers that severely degrade ferroelectric properties. The detrimental effect of such regions will be enhanced in ultrathin ferroelectric thin films, and hence play a critical extrinsic role in size effect studies of ferroelectrics. (C) 2004 American Institute of Physics.