N. Cavadini, W.
Henggeler, A. Furrer, H.-U. Güdel, K. Krämer and H. Mutka
Magnetic excitations in the quantum spin system KCuCl3
Eur. Phys. J. B 7, 519-522 (1999)
Abstract:
An inelastic neutron scattering study of the magnetic properties in the spin 1/2
double chain insulator KCuCl3 is presented. Above a spin gap of
2.6 meV
well-defined excitations are observed which are dispersive in all
directions of reciprocal space. Both the energy and the spectral weight of the
excitations can be quantitatively described by a model based on a singlet
nonmagnetic ground state and dispersive singlet-triplet modes. The relevant
feature in the model description are weakly coupled dimers. Confirmation of the
triplet nature of the excitations and of the robustness of the theoretical
approach is provided by the observed three-fold splitting of the modes in a
magnetic field. The information deduced from the measurements is discussed and
compared to earlier works on the subject.