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

The infrared spectra of the one-dimensional antiferromagnet LiCuVO4 are measured in the frequency range from 10 cm(-1) to 10000 cm(-1) and at temperatures front 2 K to 300 K. for the electric field vector E of the radiation polarized either along the a- or along the b-crystallographic directions. For each polarization six infrared active phonon modes are observed in accordance with factor group analysis of the crystal structure of LiCuVO4. The theoretical group analysis of the possible spinel low-symmetry phases is performed within the framework of Landau's theory of phase transition:,, The parameters of several phonon lines show noticeable anomalies around 150 K where the magnetic correlations appear in the copper chains, which may indicate a finite interaction between the phonon and the magnon subsystems in LiCuVO4.