Abstracts 2001

Abstract of Publication No. 407

N. Cavadini, A. Furrer, H.-U. Güdel, K. Krämer, H. Mutka and A. Wildes
Polarization Study of the Singlet-Triplet Modes in a Quantum Spin System
Proc. ILL millennium symposium, 145-146 (2001)      Full Text (PDF)      DOI-Link     

Abstract: S=1/2 dimer clusters are an excellent example for singlet-triplet magnetic units which can be assembled into spin chains, spin ladders or more complicated models of quantum magnetism. The microscopic characterization of the resulting ground-state and elementary excitations constitutes a lively research field, involving neutron scattering at its forefront. In Cu2+ KCuCl3, S=1/2 dimers are at the origin of well-defined singlet-triplet modes, which propagate in reciprocal space above a finite energy gap of quantum nature. The spin symmetry of these collective quantum excited states was investigated by polarized neutron scattering on single crystals. Complete experimental results concerning the transversal and longitudinal components of the triplet modes are presented in the context of an S=1/2 dimer model. The assumption of spin isotropic Heisenberg interactions finds confirmation in the polarization factors measured along the three crystallographic axes.

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