Infrared spectra and lattice vibrations of the spin-chain compound LiCuVO4

The infrared spectra of the one-dimensional antiferromagnet LiCuVO4 are mea sured in the frequency range from 10 cm(-1) to 10000 cm(-1) and at temperat ures front 2 K to 300 K. for the electric field vector E of the radiation p olarized either along the a- or along the b-crystallographic directions. Fo r each polarization six infrared active phonon modes are observed in accord ance with factor group analysis of the crystal structure of LiCuVO4. The th eoretical group analysis of the possible spinel low-symmetry phases is perf ormed within the framework of Landau's theory of phase transition:,, The pa rameters of several phonon lines show noticeable anomalies around 150 K whe re the magnetic correlations appear in the copper chains, which may indicat e a finite interaction between the phonon and the magnon subsystems in LiCu VO4.