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Publication Citation: Ferroics: Magnetic-Compass Lattice and Optical Phonon Dispersions of Dipolar Crystals

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Author(s): Takeshi Nishimatsu; U Waghmare; Yoshiyuki Kawazoe; Benjamin P. Burton; Kazutaka Nagao; N. Saito;
Title: Ferroics: Magnetic-Compass Lattice and Optical Phonon Dispersions of Dipolar Crystals
Published: Date Unknown
Abstract: We report a simple safe and attractive pedagogic demonstration with magnetic compasses that facilitates an intuitive understanding of the concept that ferromagnetism and ferroelectricity do not result from dipole-dipole interactions alone. Phonon dispersion relations were calculated for a 3-dimensional simple-cubic dipole crystal and a 2-dimensional square-lattice dipole crystal. The latter calculation corresponds to the compass demonstration that confirm the antiferro ground state structure. A sum rule for the three optical phonon frequencies is discussed. A mathematical non-analyticity in the longitudinal optical phonon are also illustrated.
Citation: American Journal of Physics
Volume: 66
Keywords: dipole-dipole interactions;ferroelectricity;ferromagnetism;phonons
Research Areas: Characterization, Ceramics