FTIR absorption study on GdSr2RuCu2O8 across the magnetic transition

Low temperature infrared absorption measurements have been carried out on GdSr2RuCu208 between 300 K-10 K. Most changes are seen in modes corresponding to vibrations of ruthenium, planar oxygen and apical oxygen atoms. The enhanced changes observed in the mode frequencies of these atoms across the magnetic transition over and above that dictated by anharmonicity are attributed to the spin-phonon interaction. The decrease in asymmetry of the phonon lineshape of the apical oxygen mode indicates a decreased coupling of this phonon mode with the charge carriers below the magnetic transition temperature. (author)