2018/12/16 by Anna N. Morozovska, Eugene A. Eliseev, Eugene А. Eliseev
Engineering · Materials Science · Physics and Astronomy · #Acoustic Wave Resonator Technologies #Composite material #Condensed matter physics #Coupling (piping) #Dielectric #Dispersion (optics) #Dispersion relation #Ferroelectric and Piezoelectric Materials #Materials science #Nanotechnology #Nonlocal and gradient elasticity in micro/nano structures #Optics #Optoelectronics #Phonon #Physics #Soft modes #Spatial dispersion #Thin film #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.99.115412
published as Phys. Rev. B 99, 115412 (2019) · 29 pages, 4 figures and appendix; to be submitted to Physical Review B. New section III.F added in this version
arxiv created 2018/12/16 · openalex created_date 2018/12/22 · openalex publication_date 2019/03/11 · arxiv updated 2019/03/27 · openalex updated_date 2026/08/05
Using Landau-Ginsburg-Devonshire theory, we derive and analyze analytical expressions for the frequency dispersion of soft phonon modes in nanosized ferroics and perform numerical calculations for a thin SrTiO3 film. We revealed the pronounced ``true'' size effect in the dependence of soft phonon spatial dispersion on the film thickness and predict that it can lead to the ``apparent'' or ``false'' size effect of dynamic flexoelectric coupling constants. Also, we derived analytical expressions describing the influence of finite size effect on the appearance and properties of the incommensurate spatial modulation induced by the static flexoelectric effect in ferroic thin films. To verify the theoretical predictions experimental measurements of the soft phonon dispersion in nanosized ferroics seem urgent.