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



Takeshi Nishimatsu, U Waghmare, Yoshiyuki Kawazoe, Benjamin P. Burton, Kazutaka Nagao, N. Saito


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.
American Journal of Physics


dipole-dipole interactions, ferroelectricity, ferromagnetism, phonons


Nishimatsu, T. , Waghmare, U. , Kawazoe, Y. , Burton, B. , Nagao, K. and Saito, N. (2021), Ferroics: Magnetic-Compass Lattice and Optical Phonon Dispersions of Dipolar Crystals, American Journal of Physics (Accessed September 26, 2023)
Created October 12, 2021