Dependence of Soft Phonon Spectra on Flexoelectric Cou-pling in Ferroelectrics

Abstract

Analytical expressions describing the frequency dispersion of the soft transverse acoustic (TA)and optic (TO) phonon modes in uniaxial ferroelectrics, as well as their dependence on theflexoelectric coupling constant f, have been analyzed in the framework of the Landau–Ginzburg–Devonshire theory. A critical behavior of the TA mode with respect to the f magnitude isrevealed.