Spin-Phonon Coupling inCuGeO3

Abstract
The lattice dynamics of the spin-Peierls (SP) system CuGeO3 have been analyzed by inelastic neutron scattering combined with shell model calculations. The low-lying modes of the symmetry of the structural distortion in the dimerized phase are identified and studied as a function of temperature. Surprisingly, the static distortion in the SP phase does not correspond to one eigenmode of the high symmetry phase. The two modes associated with the structural distortion exhibit frequency shifts and pronounced linewidth broadening well above the transition temperature; however, there is no soft mode behavior for these modes.