Dynamics of order-disorder-type ferroelectrics and anti-ferroelectrics

Abstract

Abstract The dynamics of order-disorder-type ferroelectrics and anti-ferroelectrics is discussed with reference to recent theoretical and experimental investigations. Following a short review of the lattice dynamical theory of structural phase transitions the pseudo-spin formalism appropriate for order-disorder-type systems is introduced. It is shown that most dynamical properties of such systems can be described by a pseudo-Ising model in a transverse tunnelling field. Finally, the predictions of the pseudo-spin wave theory are compared with some recent experiments.