Nature of magnetic excitations in CuGeO3

We report and discuss recent results obtained by means of the polarized-neutron inelastic-scattering technique and the "three-dimensional" neutron-polarization analysis on the low-energy excitation spectrum of the inorganic "spin-Peierls" compound CuGeO3. Quite surprisingly, a strong rotation of the final neutron polarization P-f is observed when the incident polarization P-i is set parallel or perpendicular to the scattering vector Q in the (b, c) basal plane. The origin of this effect will be discussed in the light of the neutron-polarization theory. We will show, in particular, that it can only be attributed to the inelastic-nuclear-magnetic-interference terms. (C) 2000 Elsevier Science B.V. All rights reserved.