Switchable ferroelectric Langmuir-Blodgett films prepared from the fer
roelectric copolymer of vinylidene fluoride with trifluoroethylene P(V
DF-TrFE) manifest the true bistability for films thicker than 15 monol
ayers; thinner films are still switchable but monostable. The crossove
r of the switching behaviour presents the first estimation of the ferr
oelectric correlation length, xi approximate to 75 Angstrom.