Study on the mechanism of switching dynamic of ferroelectric bilayers by using Landau theory

We consider a bulk system of ferroelectric bilayer with an antiferroelectric
interface coupling between two similar materials which have
second-order phase transitions. Landau theory and Landau–Khalatnikov
equation are used to study the dynamic switching phenomenon of
this ferroelectric bilayers under a step electric field. A bilinear coupling
that achieved a symmetry condition is taken into account in the
Landau free-energy expression. We found that switching time is
decreased for the system of weak antiferroelectric interface coupling,
as well as for the system when the thickness ratio between the two
layers is large. It is shown here by dynamic switching that the polarization
reversal occurs in one step in the contrary to the static dielectric
hysteresis loop. Negative and positive peaks of switching current
is discussed.