The ferroelectric modes of liquid crystals which allow for easy reorientation of the direction of polarization make liquid crystals an attractive element to use for applications such as optical storage, and optical switching. Three schemes for achieving ferroelectricity are discussed: chiral smectic alignment, achiral “banana-shaped” smectic alignment, and the nematic phase that comes from stro...

We report the first direct transition from a paramagnetic and paraelectric phase to an incommensurate multiferroic in the triangular lattice antiferromagnet RbFe(MoO4)(2). Ferroelectricity is observed only when the magnetic structure has chirality and breaks inversion symmetry. A Landau expansion of symmetry-allowed terms in the free energy demonstrates that chiral magnetic order can give rise ...

Co-doping BaTiO 3 with (X 3+ , Y 5+ ) transition metal ions improves its optical absorption properties while retaining good ferroelectricity.

Abstract The scale-free ferroelectric polarization of fluorite M O 2 ( = Hf, Zr) due to flat polar phonon bands are promising for nonvolatile memories. Defects also widely introduced improve the emergent ferroelectricity. However, their roles still not fully understood at atomic-level. Here, we report a significant effect point-defect-driven flattening with more modes and contribution in doped ...

Monophase intergrowth Bi3TiNbO9–Bi4Ti3O12 BTN-BIT ceramics were synthesized by solid-state reaction method. In the temperature dependence of dielectric permittivity, two anomalies appeared at 945 and 1114 K, respectively. The ferroelectric hysteresis loop measurement revealed that the 2Pr is 20 C/cm 2, nearly as twice as that of the BTN ceramic. The crystal structure analysis indicated that the...

We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO3 layers adjacent to them. Tc was tun...

Resonant magnetic x-ray scattering at the Gd L2 edge is used to investigate the magnetic order of the Gd moments in multiferroic GdMnO3 at low temperatures. We present high magnetic field data on the magnetic ordering of Gd in the ferroelectric phase of GdMnO3. Our findings reaffirm the important role of the Gd moments in the symmetric magnetic exchange striction responsible for ferroelectricit...

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We examine the application of short-circuit electrical boundary conditions in density-functional theory calculations of ferroelectric thin films. Modeling PbTiO3 films with metallic electrodes, we demonstrate that under periodic boundary conditions of supercells, short-circuit conditions for the electrodes are equivalently satisfied in two repeated slab geometries: a PbTiO3/metal superlattice g...

We present the refinement of the crystal structure of charge-ordered LuFe2O4, based on single-crystal x-ray diffraction data. The arrangement of the different Fe-valence states, determined with bond-valence-sum analysis, corresponds to a stacking of charged Fe bilayers, in contrast with the polar bilayers previously suggested. This arrangement is supported by an analysis of x-ray magnetic circu...