A method of measuring the phenomenological Landau-Ginzburg coefficients in
an expansion of the free energy of ferroelectrics near the phase transition
is proposed. This method is based on simultaneously recording five Fourier
components of the current response to a sinusoidal voltage as a function o
f temperature. An analysis is made of a specific application of the method
to Langmuir-Blodgett ultrathin ferroelectric films. (C) 2000 MAIK "Nauka/In
terperiodica".