https://doi.org/10.1007/s100510050642
Magnetic excitations in the quantum spin system KCuCl3
1
Laboratory for Neutron Scattering,
Eidgenössische Technische Hochschule Zürich & Paul Scherrer
Institut, 5232 Villigen PSI, Switzerland
2
Institut für Anorganische Chemie, Universität
Bern, 3000 Bern 9, Switzerland
3
Institut Laue-Langevin, B.P. 156,
38042 Grenoble Cedex 9, France
Received:
6
August
1998
Revised:
18
November
1998
Accepted:
9
December
1998
Published online: 15 February 1999
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 
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.
PACS: 75.30.Et – Exchange and superexchange interactions / 75.10.Jm – Quantized spin models / 78.70.Nx – Neutron inelastic scattering
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999
