ELASTIC AND INELASTIC NEUTRON STUDY OF CUGEO3

Elastic and inelastic neutron scattering was used to probe the structural and magnetic properties of polycrystalline CuGeO3. The diffraction data show that the chemical lattice remains stable in the measured temperature range 1.5 K less-than-or-equal-to T less-than-or-equal-to 296 K. At low temperature the inelastic experiments revealed a well defined magnetic excitation at 15 meV, which persists up to T = 50 K. The analysis of the spin-wave spectrum is based on a one-dimensional Heisenberg model within the spin-wave theory. On the other hand, no evidence of energy-gap opening, which would result from a dimerization of the Cu chains, could be found at low temperature.