MAGNETO-RAMAN STUDY ON CUGEO3

GuCeO(3) has recently gained a lot of interest as it is the first inor ganic compound that undergoes a spin-Peierls transition (T-SP = 14 K). We study the spin-Peierls state in this material in external magnetic fields by means of Raman spectroscopy. The experiments are carried ou t over a wide range of temperatures (2-50 K) and magnetic fields (0-15 T). Spin-phonon interaction, which is intrinsic to the spin-Peierls s tate, manifests itself in form of a pronounced Fano-lineshape of the p eak at 107 cm(-1) as well as several magnon-phonon coupled modes. We p resent a detailed analysis of the magnetic-field and temperature depen dence of these excitations. Furthermore, we report details of a newly observed mode related to the incommensurate phase at high magnetic fie lds and low temperature (>12.5 T at 2 K).