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TT: Tiefe Temperaturen

TT 16: Eindimensionale Spinsysteme

TT 16.7: Vortrag

Mittwoch, 29. März 2000, 16:45–17:00, H18

Consistent Mapping of Spectroscopic Data onto Thermodynamic Quantities in the low-dimensional Spin Dimer Compound SrCu₂(BO₃)₂ — •P. Lemmens¹, M. Grove¹, M. Fischer¹, N. van Eldik¹, G. Güntherodt¹, H. Kagejama², K. Onizuka², and Y. Ueda² — ¹2. Physikalisches Institut, RWTH Aachen, 52056 Aachen, Germany — ²ISSP, University of Tokyo, Tokyo 106-8666, Japan

The compound SrCu₂(BO₃)₂ is a quantum spin system with an arrangement of orthogonal spin dimers, an exact singlet ground state and a spin gap Δ₀₁=34K. Triplet excitations in this compound are extremely localized and strongly interacting due to the strong inherent frustration. In Raman light scattering experiments, in addition to magnetic bound states with energies close to 2Δ₀₁, a continuum of triplet excitations and quasielastic scattering are observed. The intensities of these scattering contributions were successfully mapped onto thermodynamic data, i.e. the magnetic contribution to the specific heat and the susceptibility. A comparison of the magnetic bound states with similar states found in dimerized spin chain and spin ladder systems allows to draw conclusions about the importance of the exchange topology for the triplet-triplet interaction.
Work supported by DFG through SFB 341.