A ug 2 00 1 Magnetic Excitations in the Spin Gap System
نویسندگان
چکیده
TlCuCl 3 has a singlet ground state with the excitation gap ∆ = 0.65 meV. The magnetic excitations in TlCuCl 3 have been investigated by means of neutron inelastic scattering experiments. The constant-Q Q Q energy scan profiles were collected in the a * − c * plane. A well-defined single magnetic excitation mode was observed. The dispersion relations along four different directions were determined. The lowest excitation occurs at Q Q Q = (h, 0, l) with integer h and odd l, as observed in KCuCl 3. A cluster series expansion up to the sixth order was applied to analyze the dispersion relations, and the individual exchange interactions were evaluated. It was demonstrated that TlCuCl 3 is a strongly coupled spin-dimer system.
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