Neutron and x-ray scattering studies of the lightly doped spin–Peierls system Cu1−xCdxGeO3

Single crystals of the lightly doped spin–Peierls system Cu1−xCdxGeO3 have been studied using bulk susceptibility, x-ray diffraction, and inelastic neutron scattering techniques. We investigate the triplet gap in the magnetic excitation spectrum of this quasi-one-dimensional quantum antiferromagnet, and its relation to the spin–Peierls dimerization order parameter. We employ two different theoretical forms to model the inelastic neutron scattering cross section and χ''(Q,ω), and show the sensitivity of the gap energy to the choice of ). We find that a finite gap exists at the spin–Peierls phase transition.