Abstract of Publication No. 329
The magnetic excitations in the double-chain compound KCuCl3
have been investigated by inelastic neutron scattering. Above an
excitation gap of 2.6 meV well-defined
modes are observed which are dispersive in all directions of reciprocal space. A model
based on a nonmagnetic dimerised ground state and dispersive singlet-triplet
excitations can quantitatively describe the excitations.