Flexocoupling impact on the generalized susceptibility and soft phonon modes in the ordered phase of ferroics

Abstract

Flexoelectric effect impact on the generalized susceptibility and soft phonons dispersion was not studied in the long-range ordered phases of ferroics. The gap in the knowledge motivated us to establish the impact of the flexocoupling on the correlation function of the long-range order parameter fluctuations in ferroelectric phase of ferroics with local disordering sources. Within Landau-Ginzburg-Devonshire approach we obtained analytical expressions for the generalized susceptibility and phonon dispersion relations in the ferroelectric phase. Unexpectedly, the joint action of static and dynamic flexoelectric effect induces non-diagonal components of generalized susceptibility, which amplitude is proportional to the convolution of the spontaneous polarization with flexocoupling constants. The flexocoupling essentially broaden the k-spectrum of generalized susceptibility and so decreases the correlation radii, as well as leads to the additional "pushing away" of the optical and acoustic soft mode phonon branches. The contribution of spontaneous polarization via ferroelectric nonlinearity and electrostriction mechanisms can lead to both broadening and narrowing on the susceptibility k-spectrum. Due to the joint action of flexoelectric coupling and spontaneous polarization the degeneration of the transverse optic and acoustic modes disappears in the soft phonon spectrum in a ferroelectric phase in comparison with the spectra in a paraelectric phase. These effects have been studied quantitatively for ferroelectric lead zirconate titanate using realistic values of static and dynamic flexocouplings and cubic symmetry approximation for the elastic properties. Also we derived general expressions for correlation function for arbitrary symmetry, elastic and electrostrictive anisotropy.

20 pages, 3 figures

References in corpus (4)

• Strain gradient induced polarization in SrTiO3 single crystals
• Understanding the origins of the intrinsic dead-layer effect in nanocapacitors
• Dynamic flexoelectric effect in perovskites from first principles calculations
• Correlation Between Structure And C-Afm Contrast Of 180-Degree Domain Walls In Rhombohedral Bati03

Cited by in corpus (17)

• Defect driven flexo-chemical coupling in thin ferroelectric films
• Oxygen vacancies induced ferroelectricity in relaxors with ABO3 structure
• The influence of elastic strain gradient on the upper limit of flexocoupling strength, spatially-modulated phases and soft phonon dispersion in ferroics
• Missed surface waves in non-piezoelectric solids
• Flexocoupling induced soft acoustic mode and the spatially modulated phases in ferroelectrics
• Pressure effect on the formation kinetics of ferroelectric domain structure uner first order phase transitions
• Analytical model and dynamical phase-field simulation of terahertz transmission across ferroelectrics
• Hidden Symmetry of Flexoelectric Coupling
• Phase diagram of ferroelectrics with tricritical and Lifshitz points at coupling between polar and antipolar fluctuations
• Flexocoupling impact on the kinetics of polarization reversal
• Theory of nonlinear terahertz susceptibility in ferroelectrics
• Size effect of soft phonon dispersion law in nanosized ferroics
• Flexocoupling-induced phonons and ferrons in van der Waals ferroelectrics
• Probing phonon softening in ferroelectrics by the scanning probe microwave spectroscopy
• Symmetry of flexoelectric response in ferroics
• The Influence of Electric Field on the Anisotropic Dispersion of the Flexocoupling Induced Phonons and Ferrons in Van der Waals Ferrielectrics
• Flexoelectricity induced spatially modulated phases in ferroics and liquid crystals (Author review)