Is there an intrinsic dead layer effect at ferroelectric surfaces?

We extend the Thomas theory of ferroelectricity to thin ferroelectric films, in the paraelectric regime above the transition temperature. We find that there is a 'dead layer effect' reducing the polarization at the surface below the bulk, and make specific predictions as to its behavior. The results are compared with recent data on thin films of strontium titanate (STO). © 1998 Academic Press Limited.