A Note on Mixed Phonon Modes

概要

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The relation between the temperature dependence of the spectroscopically-observable phonon-frequency square, ω^2_o of the optical mode or ω^2_A of the acoustic mode, and that of relevant thermodynamic coefficients is considered. A special emphasis is laid on the piezoelectric or sublattice-piezoelectric interaction between optical and acoustic modes in the lattice where not all the constituent atoms occupy the center of symmetry. The temperature dependence of the bilinearly-coupled-mode frequency is found to deviate from that of the renormalized thermodynamic parameters observed experimentally, which results in some modification of the Lyddane-Sachs-Teller relation. The mixing of interacting phonons, their normal modes and possible strain-induced ionic-site displacements are also discussed.
社団法人日本物理学会の論文
1995-05-15