THE LATTICE EVOLUTION OF THE SPIN-PEIERLS MATERIAL CUGEO3 STUDIED BY NEUTRON-SCATTERING

CuGeO3 is an inorganic compound which possesses a spin-Peierls transit ion. We have studied the crystal structure and the phonon dynamics of CuGeO3 by neutron scattering. We found that a lattice anomaly starts t o evolve significantly above the transition temperature, T-sp, and the re is a drastic change below T-sp. The phonon mode over a wide energy range changes drastically at high temperature. Therefore we conclude t hat the inherent structural instability in the crystal structure provi des favorable conditions for the lattice-spin interaction and inducers the spin-Peierls transition, i.e. lattice dimerization.