Abstract
Temperature-dependent Raman spectra of polycrystalline ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{O}}_{3}$ samples, referred to as ${\mathrm{LaMnO}}_{3+\ensuremath{\delta}}$ for convenience, were correlated to their structural and magnetic properties for different $\ensuremath{\delta}.$ For $\ensuremath{\delta}<~0.05,$ a softening of the $\ensuremath{\sim}610 {\mathrm{cm}}^{\ensuremath{-}1}$ Raman mode is observed below the magnetic ordering temperature. This softening is reduced as $\ensuremath{\delta}$ increases from 0.00 to 0.05. This behavior is not associated with lattice anomalies, and is interpreted in terms of a spin-phonon coupling caused by a phonon modulation of the superexchange integral. A quantitative analysis of this effect is presented.
Published Version
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