Spin-phonon coupled modes in the incommensurate phases of doped CnGeO(3) -art. no. 245413

The doping effect of the folded phonon mode at 98 cm(-1) was investigated o n Si-doped CuGeO3 by magneto-optical measurements in the far-infrared regio n under a high magnetic field. The folded phonon mode at 98 cm(-1) appears not only in the dimerized phase but also in the dimerized-anitiferromagneti c phase on the doped CuGeO3. The splitting was observed in the incommensura te (IC) phase and the antiferromagnetically ordered incommensurate (IAF) ph ase above H-C. The split-off branches exhibit a different field dependence from that of the pure CuGeO3 in the vicinity of H-C, and the discrepancy in the IAF phase is larger than that in the IC phase. This is caused by the i nteraction between the solitons and the impurities.