On the microscopic mechanisms behind hyperferroelectricity

Abstract

Hyperferroelectrics are receiving a growing interest thanks to their unique property to retain a spontaneous polarization even in presence of a depolarizing field. Nevertheless, general microscopic mechanisms driving hyperferroelectricity, which is ascribed to the softening of a polar $LO$ mode, are still missing. Here, by means of phonons calculations and force constants analysis in two class of hyperferroelectrics, the ABO${}_3$-LiNbO3-type systems and the prototypical hexagonal-ABC systems, we unveiled common features in the dynamical properties of a hyperferroelectric behind such $LO$ instability: negative or vanishing on-site force constant associated to the cation driving the $LO$ polar distortion, and destabilizing cation-anion interactions, both induced by short-range forces. We also predict possible enhancement of the hyperferroelectric properties by applying an external positive pressure; pressure strengthens the destabilizing short-range interactions. Particularly, the increase in the mode effective charges associated to the unstable $LO$ mode under pressure suggests an eventual enhancement of the $D$=0 polarization under compressive strain.

References in corpus (18)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Phonons and related properties of extended systems from density-functional perturbation theory
• The PseudoDojo: Training and grading a 85 element optimized norm-conserving pseudopotential table
• First-principles theory of ferroelectric phase transitions for perovskites: The case of BaTiO3
• The physics of dynamical atomic charges: the case of ABO3 compounds
• Lattice dynamics of BaTiO3, PbTiO3 and PbZrO3: a comparative first-principles study
• Two-Dimensional Hyperferroelectric Metals: a Different Route to Ferromagnetic-Ferroelectric Multiferroics
• Hexagonal $ABC$ as semiconducting ferroelectrics
• Hyperferroelectrics: proper ferroelectrics with persistent polarization
• Coulomb interaction and ferroelectric instability of BaTiO3
• Origin of Polar Distortion in LiNbO3-type "Ferroelectric" Metals: Role of A-site Instability and Short-Range Interactions
• First-principles study of the ferroelectric Aurivillius phase Bi2WO6
• Intertwined Rashba, Dirac and Weyl Fermions in Hexagonal Hyperferroelectrics
• High-throughput first principles search for new ferroelectrics
• First-principles study of (Ba,Ca)TiO${}_3$ and Ba(Ti,Zr)O${}_3$ solid solutions
• Control of polymorphism during epitaxial growth of hyperferroelectric candidate LiZnSb on GaSb (111)B
• From latent ferroelectricity to hyperferroelectricity in alkali lead halide perovskites

Cited by in corpus (3)

• Ferroelectricity and multiferroicity in anti-Ruddlesden-Popper structures
• Lattice dynamics and mixing of polar phonons in the rare-earth orthoferrite TbFeO${}_3$
• Polar phonons and magnetic excitations in the antiferromagnet CoF${}_2$