Physical Review Letters
Quantum Spin Dynamics of an S=3/2 Heisenberg Antiferromagnetic Chain: Inelastic Pulsed Neutron Scattering from CsVC l3
Shinichi Itoh, Y. Endoh, Kazuhisa Kakurai, Hidekazu Tanaka
Abstract
Well-defined spin-wave excitations were observed by using pulsed neutrons from CsVC${\mathrm{l}}_{3}$, an $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3/2$ Heisenberg antiferromagnetic chain. The observed spin-wave dispersion relation shows an enhancement of the excitation energy by a factor of 1.26, which must be compared with the quantum renormalization factor of $\ensuremath{\pi}/2$ for an $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ system. The linewidth of the spectrum at 40 K was broad and independent of $q$. The $q$-independent linewidth is the first experimental observation, which was predicted by rigorous theories for a classical chain at sufficiently low temperature.